Raspberry pi 400 setup on legends machine

Im sure this has probably been discussed here but I didnt see it. Can anyone help with connecting Ras Pi 400? Cant get the Legend Ult controls to work. Can only use bluetooth controller to play Retropie. OTG mode keeps saying "USB Connected, Legends Ultimate can not be used". The machine wont allow me to configure the Leg Ult controls to play Retropie. Any help would be appreciated.