Nextcloud crash, integrating existing user

I had a nextcloud up and running on my:

Everything was running smooth until the vacuum robot got to it.

Now all I have left is my SSD with all the file I put in the cloud. Sadly there are about 50GB of data that are only on this SSD and nowhere else. I know, I know, I should have I multiple times but well I don’t.

I got a new nextcloud up and running and in a place where the robot can’t get to it.

How do integrate the existing users and their files, without data loss and that the database is happy with it.
I looked in the documentation but I can’t find anything related to that…

You just have the data of your old Nextcloud setup, not the database and the config file?