Hello support of USBCANFD device is now under development along with adding support of CAN-FD transport protocol. We plan to release it by end of June as new experimental feature.
Anyway, you can still try the USBCAN device and try to observe the bus (and bit timing) using a logic analyzer or oscilloscope. The issues I talked about with USBCAN are causing the FreeMASTER to crash of hang. If you can press the "Test Connection" button without a crash, then, I think, the USBCAN device could work.
There is a LED on the USBCAN device - it shall flash when you press the Test Connection in the FreeMASTER - that would be a good indication if a CAN frame is transmitted or not.
Regards,
Michal