Make VERY certain that you are getting the right product.
the MyCloud Home™ product will NOT do what you want. It does not work like a normal NAS.
The MyCloud (Gens 1 and 2) can do what you want if you plug it into a wifi enabled gigabit router, using a windows file share. (windows will mount the MyCloud’s share as a drive, and then you can point photoshop there.)
The MyCloud Mirror™ will also work, like above, as will the EX2 and EX2-Ultra.
The Mirror and EX2 also support iSCSI, which a windows host can mount using iscsi initiator (a windows component), which acts as if you plugged in a disk drive, even though it is over your network. (it is a SAN protocol.) Only one computer should attach to an iSCSI LUN at a time though, unless you like filesystem corruption. (Any number of computers can access the windows file shares though.)
Depending on what you want out of the product, that should dictate your purchase decision.
The single bay units are great for a home environment that gets light use. Situations include:
Use with a (single) smart TV that can handle DLNA
A single point to store frequently exchanged data files
light use in a shared data situation (say, a lan party, for distributing spawn copies.)
The dual drive units (Mirror, EX2, EX2 ultra), in order-- provide increasing degrees of fault tolerance, and performance up to moderate use. Things like having multiple smart tvs playing DLNA content at the same time, etc. (they have faster processors and more ram the further up the foodchain you go.)
Leaving the consumer market, and entering small business class, you get the EX4 and pals.
These are really geared for incorporation into active directory and managed by a small to medium size enterprise. None of the WD NAS solutions are really appropriate for large enterprises. There are much better solutions for that sector. (See for instance, the offerings from NetApp) I only mention this top tier for completeness.
The single bay units are currently slated to be discontinued though. WD is trying hard to push people toward the Home™, but keep in mind that this is NOT going to service your needs.
Now is a good time to get a single or dual bay unit. Ralphael recently posted to an ebay seller that is offering them at half normal retail.