External storage -HD mounted but not accesible

Installed Nextcloud 11 on Raspbian Raspberrypi3. I am able to mount drive and the indicator in Nextcloud does turn green. However, I can’t access it afterwards. Is there a tutorial or commands I can follow to mount a drive while giving it permission to be accessed by not just the owner. (I think this might be the problem) In case this is a problem with nextcloud, How do I fix it?

Hi Erick,
please follow this guide: Storage to your Nextcloud
I mounted my hdd (/etc/fstab) to Nextclouds data directory but you could also mount your hdd and configure this drive as external storage in Nextclouds admin panel.
Perhaps you will find more relevant information here (Nextcloud installation guide).
Don’t forget to set

‘filesystem_check_changes’ => 1,

in your config.php.
Cheers, Carsten

Tried, however, this didn’t solve the problem. I replaced owncloud with nextcloud, also sdb with sda. However, for ‘nginx’ user, what should I replace that with?