Hi. Is there a way to rent a vServer from Hetzner or awa. Install Nextcloud and using Storj as backend.
And then setup it that the administrator from the data center have no acces to my data ?
You can certainly rent a system and install Nextcloud and configure it to use S3/Storj. The datacenter admins have no interest in your data: and you don’t have to give them an account to login. But any admin with physical access to a server (that doesn’t require some sort of manual disk decryption key during boot) can get in if they have the need.
But their corporate polices are to ignore your private data. Trying to access it without law-enforcement or similar requesting it would get them fired.
Honestly you’re not that important. They don’t care. They just need to keep things running so customers pay their bills.
This is not related to Storj, this is related to a general security, how to protect your data on the rented server be inaccessible for a datacenter admins. Storj cannot help here, unless you will not keep your S3 creds/access grant on the server and would provide them every time when you want to get an access yourself and remove them after. However, in that case I do not see a reason to have a Nexcloud running 
But Storj can be used as a backup storage, but you would provide your access grant every time when you would like to make a backup snapshot and remove after.
The alternative way for encrypted backups is to use Restic, it requires to provide a password to unlock the remote storage, you also can configure it using WORM access grant, then admins would be unable to decrypt your backups even after they would get such an access grant.
Or you may also configure the access grant with a write only permissions, in that case you can store your data, but this access grant will not allow to see or read it, even if someone get this access grant. But you still will be able to read it using your own full access grant or the Storj Console (web UI). You only need to use the same encryption phrase every time.
The other idea is to configure Nextcloud with Storj bucket as an external storage or as a primary storage, but use a Cryptomator on your desktop when you access files on the Nextcloud. Then even if the admins would get an access to your Storj bucket, they also would need your encryption key used on your desktop in the Cryptomator.
You may do the same with rclone crypt, or even S3Drive.
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