so when you go to your game library, you see all of the games you own lined up in a list on the left side. right click on Among Us and a drop-down section should appear. click on the option that says Properties. you should then see a box with different tabs in it, and one of them should say Betas. click on Betas and there should be an option that says Select beta you want. click on that and press public beta and bam, you have it