the latest ios, I don't have the google drive app, it just opened it in chrome and also in safari.

Make sure you own or have permission to edit the file. That's all I can think of. I'm selecting the 'owned by me' tab on the top of the page in the browser first.

What do you mean by offline? I'm connected via wifi when doing this. If you really mean offline access I think you would have to export it from docs/drive and edit with some other program and then import it back later when you're connected to the internet. That model is not all that conducive to sharing with a group.

-David