One of the user reviews for the app complains that it will not install on his Windows 10 device. A support representative for Samsung responded to the review and reiterated to the user that Samsung Flow only works with the TabPro S, but that it will soon support all Windows 10 PCs.
"Hi Ihap. Sorry for your inconvenience. Samsung Flow is compatible with TabPro S now. But it will support all Windows 10 PCs from Windows 10 next major update (estimated early of April). Thank you," the representative said.
It's not the smoothest reply in the world, but basically it appears as though Samsung Flow will support every Windows 10 machine once the upcoming Creators Update is rolled out by Microsoft. Barring any delays, the Creators Update will arrive in April, though that part is out of Samsung's hands.
As for phone support, Samsung Flow currently works with the Galaxy S6, Galaxy S6 Edge, Galaxy S6 Edge+, Galaxy Note 5, Galaxy S7, Galaxy S7 Edge, and 2016 models of the A7 and A5. It is also a safe bet that Samsung Flow will work whatever Galaxy S8 models Samsung releases.