How can I allow for multiple Google Drive users to edit the same HTML document at a time? Whenever I use an HTML file it doesn't allow it to be edited in Drive (by me or the other user).
To edit HTML files by several users at the same time in Google Drive you need to connect an non-Google app that has that feature.
To add non-Google app,
- Go to http://drive.google.com
Click on Settings (button with a gear icon) > Manage Apps
Connect more apps.
- Search and choose for an app
- Click on
Learn more link shown in the snapshot points to Non-Google apps in Drive - Google Drive Help.