Boot up CS:GO and load into the main menu. If you got into the CS2 beta test, you'll see a popup telling you so (or else a notification in your left-hand main menu bar with a message about the beta). Just click “Enroll” on the popup, and you're good to go! You may need to restart CS:GO to play the beta.

Counter-Strike 2: how to find your test invitation Valve will inform selected candidates for the Counter-Strike 2 test in CS:GO's main menu, where you will get a notification. If you see that notification, click “ENROLL” and download CS2. Launch CS:GO after the download is done and choose “Limited Test” to play CS2.

To be eligible for a CS2 Limited Test invite players must have CS:GO Prime status, an active official competitive matchmaking Skill Group, and play majority of their official matchmaking games in one of the regions where the Limited Test is available."