PROPFIND 404 on external storage folder

Hi there, I’ve installed Nextcloud (12) on a RPI3, but I have a question regarding external storage.

I have an external disk mounted on the RPI. If I ran apache as the default user (www-data), I could see and navigate the external storage folder with no issues. The “problem” is that the disk is mounted as a user other than www-data (and I’d like to keep it that way) so, all the files that are uploaded via nextcloud, are owned by www-data.

I tried running apache with the same user the file system is mounted with, but as soon as I do that, I can’t navigate the external storage anymore. Every time I try to access wthe external storage, I get a PROPFIND 404, Not found.

I really don’t know where the problem or misconfiguration might be. Is it in Apache? is it in nextcloud? no idea. I was hoping somebody could shed some light please?