Nextcloud Permissions External HDD

Hi,

I have nextcloud (SNAP) installed and everything is working perfectly apart from being able to add or create (Or even see) any folders on my external HDD

I have run the snap command to allow access for NC to the /media/ and I can then see the shares in different NC users accounts but when I try to create a folder in there as either admin or any user, I cant. I get the forbidden message so Im sure its permissions related.

looking at a few posts and threads it says to grant appropriate permissions, could anybody let me know how to do that?

Thanks