There are three common types of engagement system depending make and model.
1) Auto. Push button on remote to engage and disengage drive rollers.
2) Manual lever. This requires single movement with lever and can take quite lot strength. Especially as typically engaging both sides at once via cost link.
3) Manual wind on. Just nut (typical 19mm as per stay) which you turn multiple times with crank or battery drill. Need to monitor a coloured gauge indicator (red,yellow green) to know how far to wind In or Out. WARNING, if not enough engagement pressure is applied, slippage can happen and van could run away on slope.
Each as pros and con, with Auto being safest and easist to use.
In all three cases make sure you chock wheels before disengaging
The Caravan Nut has great video on fitting mover.
View: https://youtu.be/dCYugFsyCO0?si=GMiHfegLeEFwPNrN
I fitted auto emove version. Mechanical installation was about 2hours. Electrical took a few more hours, straight forward just takes time to do a neat job.