I hope this is what you need:
If youâre using the built in Mail app:
In Settings, go to Mail, select Accounts, then go to Add Account. Select Google, enter your Gmail address and password. If you use 2-Step Verification, confirm that you are trying to login somewhere else (computer, âŚ). Then select, what iOS can access, and save the account.
If youâre using the Gmail app:
Open the Gmail app, go to Sign in. If the app remembers the account, you just have to confirm it and allow to receive notifications. Otherwise youâll have to add the account.
If the problem is different, please explain what isnât working, and what youâve tried so far.
Iâve merged both your threads about this issue. Keeping the information in one thread will more likely result in helpful advice.