Hello,
If you enable MIDI clock out on the H9, you should be able to sync another device to it.
Have you reached out to Meris support? I’m not sure if a MIDI convertor box is required for their stompboxes, but you may not be able to connect the H9 directly with the cable you are using. Do you have any other MIDI devices that you can try to sync the Polymoon to?
In the future, please post any H9 questions you have in our stompbox forum: https://www.eventideaudio.com/forums/forum/products/stompboxes/