Okay, I tried downloading the encrypted folder directly from the HiDrive Website (instead of webdav). The downloaded folder was then opened via Cryptomator inside my downloads-folder, and… most of the documents were missing. 
Okay, I tried downloading the encrypted folder directly from the HiDrive Website (instead of webdav). The downloaded folder was then opened via Cryptomator inside my downloads-folder, and… most of the documents were missing.