Hello,
I do not have a MIDIsport 2x2 to try out, but a simple Google search shows that the MIDIsport requires the firmware to be loaded at boot, see for instance this thread.
With respect to recognizing USB MIDI devices, Bela should be no different from other Linux computers, so any tutorial you'll find online on how to run the MIDIsport 2x2 on Linux should be able to help you through the setup.
Note that unless you connect the board to the internet (e.g.: plugging the ethernet port into your home router or sharing the connection from your laptop), you may not be able to run the various apt-get install ...
commands you will find. Here is a workaround on how to do apt-get
without internet connection.