thanks for your replies!
This is a result of "sudo armbianmonitor -u":
If I check "dmesg | grep usb" after connecting the keyboard, I see this:
[ 406.619687] usb 8-1: new full-speed USB device number 3 using ohci-platform
[ 406.802741] usb 8-1: New USB device found, idVendor=0a4d, idProduct=0090
[ 406.802761] usb 8-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 406.802770] usb 8-1: Product: USB Keystation 49e
[ 406.802777] usb 8-1: Manufacturer: Evolution Electronics Ltd.
With lsusb I see this device as:
Bus 008 Device 003: ID 0a4d:0090 Evolution Electronics, Ltd Keystation 49e Driver
That looks like the system recognized the device, the "aconnect -l" though doesn't show it in the list.
In standard desktop Ubuntu it works just fine.