Decrypt Data from Nextcloud 17.0.1


I have a problem with my nextcloud encryption.
I installed nextcloud 17.0.1 and loaded up files, some of them important. I enabled the encryption. Later I had bad problems with the installation so I decided to do a clean installation.
I saved the data directory, the mysql folder (sadly that was not the database as I thought), the whole nextcloud folder.
I simply coppied the data with mc. Now I can not open the old files that I coppied.
How can I decrypt it (I have the old keys) master and public in private and public version.
I also made me a virtualbox with ubuntu, apache2 and a clean nextcloud installation where I tried to recover data. I only work on the coppies of the data.
The occ encryption:decrypt-all doesnt make it work.

How can I make nextcloud open my files so I can dowload them without encryption?
If anyone has an idea I would love to hear it.

The module is the Default_Encryption_Module.

Best regards Lea