A Little Help, Please, with AP on Aermacchi B-339?

I recently bought the Aermacchi training jet from the in-sim Marketplace. Nice plane, 3 versions, many liveries. Even better: I was able to fly it reasonably well. But I haven't been able to figure out the AP, which is very different from that in all the other planes I have.

There appears to be no master switch to toggle AP on/off, and the Z key doesn't always have that effect, either. The panel has keys for Heading Hold and Course Hold, which light up when clicked, but the Course key seems to have no effect, and the Heading key works only sometimes, in conjunction with the Z key. Also, there are a couple of other keys that suggest they might follow the GPS, but none says so, and experimenting has yet to reveal exactly what they are supposed to do. Other planes will follow a course set to a waypoint or airport, but I don't see how you set one in this plane.

Of course, there's no Manual.

I will continue to tinker, but maybe someone here has figured it all out. Any advice will be greatly appreciated.

The MB-339 for MSFS hasn't the autopilot like in the real aircraft.

It is supposed for training and all time manual flight.

The aircraft is equipped with a flight director which indicates what attitude you need to maintain to follow a route o a ILS. The flight director can be used in conjunction with VOR, TACAN o AHRS/GPS signal, you only need to switch between VOR/TAC/RNAV pushbutton located on the right side of the HSI.

The product has also a flight manual, you can download it directly from here: https://drive.google.com/file/d/17IfhjD0qfhSZu0ezhWEWTL7k18dRfTNr/view?usp=sharing

Video tutorial for navigation here:

The MB-339 for MSFS hasn't the autopilot like in the real aircraft.

It is supposed for training and all time manual flight.

The aircraft is equipped with a flight director which indicates what attitude you need to maintain to follow a route o a ILS. The flight director can be used in conjunction with VOR, TACAN o AHRS/GPS signal, you only need to switch between VOR/TAC/RNAV pushbutton located on the right side of the HSI.

 

The product has also a flight manual, you can download it directly from here: https://drive.google.com/file/d/17IfhjD0qfhSZu0ezhWEWTL7k18dRfTNr/view?usp=sharing

 

Video tutorial for navigation here:

Thanks.

The link to the Manual is to Google docs, which says the doc can't be found.

The video is a little helpful. But if you are saying that the plane must always be flown manually, and does not lock on to a heading or altitude, my experience thus far is otherwise.