You should be able to create a normal share and then you should be able to determine from the dashboard user access and you can also check if you want to use a specific share for time machine.
This link might help you with creating a share on your unit:
You stated the question more clearly than I did. I just want to be sure that you can have unlimited shares and that you can assign each PC or Mac to its own share for backup purposes.
As with so many things, we’ll probably have to buy it to find out.
For Time Machine, you can only use 1 share in order to backup from each mac, what will make a difference is that each backup will show up with the name of each mac, so this way you can distinguish one from the other.
On a PC its different, you can use a share for each different computer depending on the software you use.