Cannot add Google Drive in Files
I don’t have Edit option when tap on More buttoon iin filess app.
Based on your screenshot, you're one screen too far.
You tapped OnMy iPhone.
You have to follow all the steps and instructions in Related Article: Use third-party cloud apps in the Files app and if you still need help, get more help and assistant from Apple directly, see Contact Apple for support and service -> Contact Apple for support and service – Apple Support (UK)