Welcome to the Cryptomator Community 
since Cryptomator only encrypts your files, you should ensure your sync works correctly. Place a normal file in your cloud storage. Do you see this file on the other devices?
If so, investigate, if your cloud provider syncs only partially. Create a new vault and place some files inside. Do you see the vault an all files inside it also from the other devices?
These files are the actual masterkey and backups after each password change. Additionally, there needs to be a d folder present.