There is a ROBLOX app already on the Windows Store for PCs. It's VERY easy to port a Windows 10 app across all devices. That's the big selling point of Windows 10 apps. So could you just check the box that lets you use Windows Mobile? Thanks!
They took the time to make a ROBLOX app for Windows desktop, which seems VERY pointless as you could just download the program from Roblox.com, so why not make something useful out of the app and push it to more platforms? That's what I think.