If after downloading the product from Google Drive you notice that not all files have downloaded, it’s likely that the download process was interrupted in some way. This can cause some files to be 'missing' despite being in the Google Drive folder.
As the file sizes are large (especially the Photoshop mockups), this can sometimes occur if the Internet speed cannot support the download of the entire folder.
In this case, what we would recommend is downloading the 'Mockups' folder separately. Or if that is still causing issues, to relieve pressure from the download process to download the individual files (depending on your Internet connection) rather than the whole product at once.