Riders Republic

You can find your Sponsors by pressing start to bring up the menu, then RB over to Progress.

When you open the Sponsors page, you’ll have three slots you can fill out. These sponsors basically give you daily missions for more cash and swag when you complete them.

If you’re fresh out of the tutorial, you will not be able to equip any sponsors right away. You can try to equip one and as you hover over your ideal sponsor, it’ll tell you the unlock requirements at the bottom of the sponsor description

The quickest ones I could see would be to reach level 7 in Bike Race/Tricks or reaching level 6 in Snow Race. I stuck with Bike Races since you’ve already had some decent progress there from the tutorial. Either way once you have satisfied the conditions for your chosen sponsor, a small tutorial screen will open and it will automatically equip the sponsor for you to unlock the achievement