Google who have upped their security settings to the point where they disable a lot of apps from accessing Google Drive, manually allowing 3rd party apps to access Google Drive does not work for Cloud Import.
The workaround is to access Google Drive through your web browser.
If you mean you need to access images from your google drive account to import within MEP. Download the images you need first onto your drive and access them from there. It is not possible to use images directly from the net within a video editor. The connection would not be fast enough in real time to load the images at the server end and the program does not deal with internet addresses to which each file would be allocated to.