I use Windows OS, so I can’t give you any detailed procedure. It appears that Mac OS doesn’t identify its USB ports as COM ports.
I can explain how you can figure it out in concept. In my command above, the ‘filter’ does a search in the description field for USB devices that match the desc. There must be a difference or you can’t identify your uArms between each other.
With both uArms plugged in, SwiftAPI() should grab the first one (by whatever scheme it use to consider first). You probably only want to plug one uArm in at a time to a specific USB port (not the same USB port for both uArm). The device info should have some differences which you can use to find a specific uArm using the filter argument in the SwiftAPI() initialization.