Yes, you can add media from Google Drive into an editing project.
Option 1
Use the direct file importing feature in Clipchamp that appears when you click on the down arrow importing media button.
A second pop-up window will appear. Choose an account to continue to Clipchamp. Click the correct email address linked to your GDrive files.
Once you have linked your Google Drive, another pop-up window will appear. Select the media file you would like to add to Clipchamp, then click on the select button.
Option 2
Download the files from Google Drive to your computer and then add them to your project from there.
If you're on a Chromebook, you can add files to your Clipchamp project from your Google Drive as well. See Using Clipchamp on a Chromebook.
