Maps Pro is able to connect to a Built-in GPS, a Bluetooth GPS, or a USB GPS, see What are the "Built-in GPS / Wifi location", "Bluetooth GPS" and "USB GPS" options? for more informations
If the USB GPS option doesn't work (some Garmin devices cannot be read by Maps Pro), you can use GPSDirect to be able to use your GPS device with Maps Pro, see our guide: How to connect to a USB GPS (GlobalSat BU 353 S4)
Note that you will not be able to install GPSDirect if you are running an "RT" version of Windows which can't execute all programs.
Maps Pro is currently the only application in the Windows Store able to read and display GPS data coming from Bluetooth and USB devices!