To be able to access a partition from own cloud one the proper permissions have to be given.
To list the partitions run the following command:
sudo fdisk -l
A list of all hard drives and partitions will follow. To mount a partition locate the one you want o mount, this should look something like /dev/sdx#. Where x represent a letter and # represent a number.
Then go to /mnt and create a folder.
This folder needs to be given the right permission and the owner needs to change as follow.
chmod 0750 hdd1/
chown www-data:www-data hdd1/
Now mount can be done with:
umount /dev/sdx# /mnt/hhd1
Remember to change the x and # accordingly. And now you should have access to the hard dive in through the folder /mnt/hhd1.