Go to Google Drive and grab the “shareable link” that Google Drive provides (you can’t use a file that is not publicly accessible). An easy way to do this is right click on your file and select “Get shareable link”.
The URL should look like this: https://drive.google.com/open?id=FILE_ID or https://drive.google.com/file/d/FILE_ID/view.
You can now upload the file to your TalentLMS course in two steps:
Move to the files section (1) and upload the file url using the "upload from external url" option (2).
To use the file into a unit, go back to your course's content and add a Presentation/Document Unit (3) and then select to "use a document from your files" (4) and select the file.
Note: The above process only applies to files uploaded to Google Drive. It will not work for files (documents, presentations, spreadsheets etc) that have been created inside Google Drive.