Before connecting your VFD to Masso you first need to make sure you have it running with external control.
You need to get it stopping and starting with the use of an external Forward switch.
If you plan on using reverse then you also need to get it working with the use of an external reverse switch. (Ignore if you don't plan on using reverse.)
Lastly you need to be able to set the speed using an external voltage. Connect a POT as shown in the manual and make sure it controls the speed.
I apologize if it sounds like I am putting you off but it is important that the VFD be properly configured before you think about connecting it to Masso. You will only make troubleshooting 10 times more difficult by adding yet another piece of equipment into the equation if you don't have it working at the most basic level.
You may already have this working so please let us know and we can move onto the next step.
See the attached drawing. You remove the POT and feed the analogue speed signal from MAsso into the AV1 terminal and connect the GND terminal to Masso -ve rail.
Remove the external switches and connect to the FWD & Reverse on Masso as shown. I have assumed your FWD & REV terminals are the default ones and have marked those on the diagram. Use the ones you used with your switches.
Go into the F1 screen,select Spindle and check VFD and enter your Maximum spindle RPM at 10 Volts as well as your spin up and spin down delays.