You can enter your date of birth (if prompted), and then sign in. If you are still locked on Quick Chat Only, you may need to ask for guardian's permission (this hint is only for PC). On phone:
1. Download Among Us.
2. After downloading enter the game.
3. You may get a notification from Among Us where needs to download additional assets.
4. After that, enter your date of birth.
5. Then sign in to your Google Account.
6. You will be prompted to choose an account to use for Among Us.
7. Click on your account.
8. Approve permission for signing-in. If you have less than 13 years, you'll be stucked at Quick Chat Only till your 13 year.
9. After approve, you should get "Success!" pop-up.
10. And you're ready to go!