So i kinda guess its not working because of that?
No that is fine. You do not need a ground to send data. The ground on the Arduino to the MIDI socket has a ground for a cable screen only. It is important that this screen is not connected to ground at both ends. That is why it is missing from that PCB.
This is normal and will not stop you sending data.
Use
noteOn(0x90, note, 0x7F);
in place of
noteOn(0x90, note, 0x45);
For maximum volume