Nextcloud can't write to exfat hard disk (Casa OS)

Hi there, first of all thank you so much for your hard work. I tried installing nextcloud separately with mariaDB but always got stuck in the setup process and this video helped a lot
My problem:
I have 2 HDD, one NTFS and another EXFAT. I’ve managed to mount both to nextcloud and both hdd shows up in /settings/admin/serverinfo
But when I try to upload files to the exfat hdd, I get this error:
Some files could not be uploaded & Operation is blocked by access control

I tried going to the logs but I couldn’t find anything Debug no app in context OCA\Survey_Client\Notifier::prepare() threw \InvalidAr - Pastebin.com

I tried changing the ownership by ssh from my pi device but I get this error
chown: changing ownership of ‘/media/devmon/HDD_2’: Operation not permitted

any help is super appreciated! I’m super new at this, been only dwelling in linux and SBC’s for a week after years of using windows.