Moved a folder locally to my nextcloud drive. Won't open anymore: Permission Denied

Operating system Raspbian Buster Lite:
Server Raspberry Pi 4
Installation Official Documentation for Raspberry not via a package on debian.

I tried to make an backup today of my nextcloud drive. So I plugged it into my main computer, and started copying everything to a second drive. After seeing that it would take about 300 hours I stopped. (I know this is not how you’re supposed to do backups).

Some folders where missing on my original drive. (I was in the ncdata folder, the only one showing when plugging the drive in). So I moved the missing data back to my nextcloud drive. Everything is back again, no data missing. I restarted the server, but when trying to access this particular folder via SMB, a message pops up with permission denied. All other folders work. When logging in on my webpage, it’s just an internal error, I can’t do anything at all.

What am I doing wrong? I think I have to relink this folder somewhere again, but when opening /var/www/nextcloud/config via SSH I have no idea what could be missing. In general, the file is pretty small, I don’t think there could be the solution.

Managing the permissions solved the issue. At least for SMB. Web page still not working, but at least SMB and the mobile Nextcloud app.