Fallout 76

One of us is the second mission and first official introduction to the Enclave faction in Fallout 76. Once you complete the mission Bunker Buster you will find a holotape titled "Welcome to Whitesprings" and a congressional bunker access card. Listening to the holotape will begin the quest One of Us.

If you need a guide for Bunker Buster I have one posted here.

Once you listen to the holotape and begin this quest, your objective will be to travel to The Whitespring Bunker.

When you first enter the bunker, it may not seem like much. Exploring the room to your immediate left will reward you with an interview article from the Charleston Herald. The interview is with none other than Senator Sam Blackwell, who as we previously learned in bunker buster, vanished from the outside world without warning. This interview is post disappearance and Mr. Blackwell makes some damning accusations against the U.S government, including they are run by a secret "sinister force".
Discovering the Enclave
Go back to the main room and use the Congressional access card on the mag-locked door in the North-East end. Using the card opens the door, but triggers a PA announcement. The mysterious voice will commend you for discovering Sam Blackwell and his key-card then making the decision to come to Whitespring. He invites you inside to discuss further opportunities to support "their collective". Continue to follow the voices directions as he guides you through the bunker. Soon you will come face to face with MODUS, the "man" who invited you in and the brains of the Enclave collective.

MODUS will explain to you that he is the central brain behind the Enclave, a secret collective that has been running the US government since the beginning, whose main objective was to seize and control as much power as possible. He expresses that you can help bring the Enclave back from extinction, but that requires you to complete a couple of tasks before he allows you to become an enclave member.
Head to the next room and interact with the Questionnaire terminal. It is unclear if your answers to this questionnaire truly matter (as there is an optional objective to skip the questionnaire all together) however the following answers yield a positive response from MODUS:
1 [Military/ Law Enforcement]
2 [Adam Smith]
3 [Ulysses S Grant]
4 [Salad Fork]
5 [General Archibald Baker]
Once completed and submitted for analyzation, interact with the Modus Terminal in the south east end of the room. He will then give you your first task to complete for the Enclave to prove you deserve to be apart of the collective.
Loading the System Access Tape
Once you get your next task, interact with the designated dispenser next to the MODUS terminal to receive the System Access tape and a Stealth Boy MKIII, your first task is to take this tape and upload it to a SigInt System Terminal located inside the Sugar Grove relay in the Savage Divide region.

head to this location and be ready to fight, as the relay will be crawling with Protectrons. It is best to save the stealth boy Modus gave you for once you are inside the relay, as the forces outside are much easier to handle than fighting the forces inside the crowded relay corridors. Once inside, activate the Stealth Boy or fight your way to the tower control center. At the front of the control center, under the green tactical map, will be the terminal you will need to access. Luckily SigInt didn't believe in terminal security, so once you access the terminal, simply use the action button to load the system access holotape into the terminal. Once complete, Modus and the Enclave will once again have access to the world outside the bunker, with the SigInt relay tower at sugar grove reestablishing their communications network.
Now it is time to head back to the Whitespring Bunker for your next task.
Deploying the Uplink Module
The next task Modus will assign you has you heading towards the National Radio Astronomy Research Center in the Savage Divide region of Appalachia.

This location, according to Modus, is the best spot to place an Enclave Uplink Module. Once inside, fight your way through any Scorched that may be present and head to the stairwell in the north end of the building. This stairwell will lead you directly to the roof of the Radio research center.
Head to the radio dish control panel and insert the uplink module you received from Modus.

This will connect him to the radio dish and give him an even stronger connection to Appalachia, even allowing him to send a resource drop crate as a thank you for your hard work.
The crate will be dropped nearby by an enclave vertibird. Head towards the drop and be ready to fight any super mutants that may be in the area. Inside the crate will be an Orbital Scan Beacon and an Orbital Strike Beacon, two new resources available to you thanks to your hard work for the enclave.

-Orbital Scan Beacon: Will scan all threats in a placed area for 30 seconds, revealing them to you

-Orbital Strike Beacon: Will mark enemies in a placed area for 30 seconds and then issue an orbital strike to dispose of them.

Once you collect the items from the supply drop, return to The Whitespring Bunker and interact with the Modus terminal once again. Modus will be proud of what you accomplished and officially invite you to join the Enclave, granting you access to the Science, Military, and Communications wings of the bunker.
This completes the mission One of Us and begins your first assignment as an official Enclave operative, Congratulations! Modus will give you your rewards for the quest and instruct you to head to the military wing of the bunker, beginning the quest Back to Basic.

Credit: https://m.ign.com/wikis/fallout-76/One_of_Us

Video Credit: “GamerForEternity”