The uniform is: "esports jersey with white swirls", "F-K University sports bra"(if character has breasts), "Joggers", "Boyshorts"(if female), "Boxer-Briefs"(if male/nonbinary), and "Sneakers".
It should all already be put together for you in an outfit you can change into in your closet.
Edit: so we discovered that the joggers were bugged and were, uh.. assless. The uniform check was just making sure all parts were covered, and everyone was running around with their butts hanging out, so if the player wasn't wearing underwear the uniform check would fail. xD
It is a very silly bug but it will be fixed in the next update.