Writing on data via SSHFS gives permission denied

Hello Communiy,

I try to mount my data storage via SSHFS using the same user I have on my nextcloud instance.

sshfs user@ncloud:/mnt/data/user/files nc-share

Unfortunately I cannot write to the files directory of my user located in data. “Permission denied”
I tried to usermod -aG www-data user add my user to the www-data groupd, but that doesnt work.
Is there a way I can write into that directory directly, or do I need to give www-data an ssh-key to sshfs with the right permissions into that directory?
Or… should I change the ownership to the remoteuser inside that Nextcloud#/mnt/data/user/files directory?

Bad idea because of the differing users.
Why not use webdav? You can mount a webdav using davfs2.