The Remote Control module isn't even there.

Reproduced.
Not available in default missions. (needs to be rebuilt?)
Not functional when used anyway. (just makes error noise)

Somehow got it working. Not sure what I changed?

Limitations mentioned on Zeus control include:
Not being able to command squads.
Not being able to enter/leave vehicles.
Chat still appearing as from you not from the controlled unit.

Personally I think that's pretty poor, and hope it's just because it's WiP and not because they can't be bothered to add the functionality (which I expect is pretty complex)

It's the missions you're trying to use. Those missions don't have the new Remote Control module built-in, if you go on the Editor (http://forums.bistudio.com/showthread.php?173333-Tutorial-How-to-make-a-Zeus-mission&p=2625744) - It'll show.

Dev version published in Friday morning was accidentally missing one addon which was required for remote control to work. Another update released in the afternoon fixed this.

Now I can't aim down sights in remote control mode.

Mass-close of resolved tickets not updated in last two weeks.