To answer your first question, there’s a community FAQ on zigbee which should be pretty clear:
FAQ: Zigbee Application Profiles, or why not all zigbee devices work with SmartThings
(For that matter the same issue applies to Wi-Fi: there are lots of Wi-Fi devices that cannot be used with smartthings because smartthings doesn’t know the right message format to send. Again to use the Postal Service analogy, you may have the right envelope, but that doesn’t mean the letter inside is written in a language that the recipient will understand.)
As far as that specific item, that’s a nice looking device! 
Unfortunately, smartthings doesn’t tend to handle multibutton Devices very well generically, you usually need specific custom code for each particular model. it doesn’t look like anybody has written any yet for that one.
(First rule of home automation: the model number matters.)
There are some similar looking Z wave devices which do work with SmartThings, but probably cost a lot more.
What country are you in? The device selection does vary somewhat.