Xander Hey Xander, sorry for my late reply. I didn’t noticed that I got an answer, because you did not mention me.
Now, to clarify you want to decrypt your files to move away from Boxcryptor, right? Boxcryptor sold their technologies to Dropbox, which is a well reason to leave Boxcryptor and use great alternatives like Cryptomator.
If so, you should try to download all your files directly from Google Drive by visiting the corresponding website. When your download is finished, unzip the archive and move it into a new folder you create. Then you mount the folder in Boxcryptor the same way as you would add another cloud storage provider. This will cause that you can access all the files in the local folder and there you either decrypt by using the right-click menu or to simply copy all the files to your designated folder.
Hope that helps. I’m in the moving process too!