I'm not familiar with the UF6. I downloaded the manual to get that information.
You can have both the USB and the MIDI connected at the same time, but I can't think of any reason to do that. The USB should work fine. I think it should be set to transmit MIDI so don't worry about that. If not, read the manual. Its decent as far as manuals go.
Dave
Computer: Intel i7, ASROCK H170M, 16GB/5TB+, Windows 10 Pro 64-bit, Sonar Platinum, TASCAM US-16x08, Cakewalk UM-3G MIDI I/F
Instruments: SL-880 Keyboard controller, Korg 05R/W, Korg N1R, KORG Wavestation EX
Axes: Fender Stratocaster, Line6 Variax 300, Ovation Acoustic, Takamine Nylon Acoustic, Behringer GX212 amp, Shure SM-58 mic, Rode NT1 condenser mic.
Outboard: Mackie 1402-VLZ mixer, TC Helicon VoiceLive 2, Digitech Vocalist WS EX, PODXTLive, various stompboxes and stuff.
Controllers: Korg nanoKONTROL, Wacom Bamboo Touchpad