This article describes an issue users can encounter with the Files Cabinet add-on when files used for the add-on are located in the 'shared with me' section.
My Drive is where all your personal files and folders are stored in Google Drive. When someone shares a file or folder with you, it is not automatically added to your (personal) My Drive.
This is the reason why any add-ons (Files Cabinet included) won't be able to access files or folders inside the Shared with me. Plus the fact that Shared with me is not a folder - but a Google Drive menu that's part of the navigation component.
Shared with me is part of the Google Drive navigation component
Step 1 - Follow the steps detailed in the article Add files to My Drive. The saved files will automatically be stored on your My Drive main page.
Step 2 - You can then organize / store / move the pertinent files into a target folder.
Step 3 - Run the Files Cabinet add-on as you normally would - specifying the target folder.
Step 4 - Refresh (reload) your app.
Once the add-on finishes creating your datasource and app, you'll be able to see the pertinent file (that was initially on your Shared with me space) is now displayed with its associated metadata (owner, file location, ...).
Google Sheets owned by the admin is now stored locally in my (personal) My Drive folder.