Clarify owner/group requirements for data folder

[rgr101]

I understand that Nextcloud loves to get www-data as owner and group of all its folders and that's the goal to achieve. But there are various installations where this utterly is not possible, eg. in shared hosting env's, or, in my special case:

Running Nextcloud in a Virtual box VM and the data folder configured (for good reason and carefully treated!) on a shared vbox folder. In this case, owner/group of this folder is - not changeable - 'root'/'vboxsf' with permissions 'drwxrwx---'.

I found out by myself that it is sufficient to get user www-data member of group vboxsf!

But in the documentation it's always stated that owner/group HAS TO BE www-data:www-data, only by digging deeper a comment like "...needs to be r/w access..." can be found.

So, a clarification of the defacto requirements - not only for the data folder but also for any Nextcloud folders - would be very helpful - thx!