Despite the confusing description, the proper way to get this achievement is to go to The Exchange in the MyTeam menu and exchange the required group of players/contracts for a special card. Currently, the easiest card to get is a Sapphire Karl Anthony Towns.*
*If you have already made this exchange for KAT in NBA 2K21 last gen, you can't get him again. You'll have to pick another one. My second pick for easiest exchange is the Diamond Contract, since you'll end up opening a lot of free packs (make sure you use the free locker codes) and will probably get more than enough contracts to dump into this exchange.