From the author's README on Thunderstore

Throwback Basketball Jerseys

23 classic basketball jerseys for ReSkate, worn over an oversized white tee, early-2000s style. Find them in Apparel > Tops.

NBA, college, All-Star, Team USA and streetball throwbacks
Round-neck and V-neck cuts, plus one worn backwards
Side slits at the hem and layered neck and armhole trim

Installation

Open the ReSkate Launcher
Click Mods
Click Install .zip
Select Throwback_Basketball_Jerseys.zip
DONE

Known issues

The jersey can clip a little with the tee or body in some poses. A fix is planned for a later update.

Install SpicyTacos Throwback Basketball Jerseys

You need ReSkate and your own copy of skate. on Steam.

Open ReSkateLauncher.exe and go to MODS.
Search for SpicyTacos Throwback Basketball Jerseys and click install. The launcher also installs anything it depends on.
Press PLAY. In game, the MODS tab of the ReSkate menu (Insert) turns it on and off.

Or install it by hand: download the .zip and drop it on the launcher window, or unzip it into its own folder in Mods\ beside Skate.exe.

Maps show up in the ReSkate menu's level list. To join a server running a custom map, you need the same map installed. If the game won't load after installing, see known issues.

skatemods doesn't host or review this mod. The download comes straight from Thunderstore. Only install mods you trust, because scripts can run code.