ownCloud plugin - Can't select or create a Data directory / Volume (nothing shows up)

I installed the ownCloud plugin.
I clicked "Enable".
I selected the certificate, and clicked on the "Data directory" + (plus) icon.
I clicked "Volume", and nothing showed up, so I can't choose a "Path", either.

This is all required, in order to enable ownCloud, so I can't enable the plugin.

NAS:
WD 3TB MyCloud (yes, I know, it's nothing like the cool setups you guys have)
Single drive

What I've tried:
1) Plugged in a USB flashdrive to see if that would create even a tiny data directory (just looking for a lead), but checked the GUI again, and it did not show up as an option.
2) "apt-get update" & "apt-get upgrade"

What I'm wondering:
1) Do I have to create a separate partition (to be the main "data partition")?

When:
"cd /var/www/owncloud/data" & "ls -l"
I get:
"total 0
lrwxrwxrwx 1 www-data www-data 53 Apr 2 2015 tmp -> /media/HardDriveUUID/Data/ /tmp"

When:
"cd /var/www" & "ls -l"
I get:
"total 8
drwxr-xr-x 7 openmediavault openmediavault 4096 Aug 1 01:37 openmediavault
drwxr-xr-x 13 root root 4096 Aug 1 02:31 owncloud"

When:
"cd /media" & "ls"
I get:
HardDriveUUID

When:
"cd /mnt" & "ls"
There's nothing (which I would assume is okay).

I hope I've provided enough information. Any suggestions?

Per @luxflow s advice, I will just not install ownCloud, because apparently, it sucks once many files are added. Instead, I'll just stick with OMV and create user profiles, from there. Thank you, luxflow.

Well... I figured it out, anyway, after I removed the plugin.

Go to "Storage".
Go to "File systems".
Click on the storage partition (for me, it was /dev/sda4).
Click "Mount".

It will show up as a "Data directory" on any plugin that requires it. (ownCloud, MySQL, etc)