Here is a photo of an older set of the bellows. You'll see three 'clips' of a sort on this set. If you look at Alex's diagram, you'll see the bellows on the left with a multitude of small clips that run continuously around the back edge. Same idea but more common. Your photo of your bellows shows the multiple clips. There is a small groove that the clips go into in the lens board.
The front of the bellows screws into the back of the lens mount. I've seen a few caseswhere it is actually possible to unscrew the bellows from the lens while in place- extend lens (bellows) and take a dental pick or such and start playing with the little tabs and see if it will rotate counter-clockwise.
A dental pick or such with a little hook can be used to unclip the bellows in place. Extend lens again for room. Start prodding and pushing. Best to protect the rear lens surface with something in case pick slips. If you get one to move forward, stop and go to the other side or 120 degrees around to avoid jamming it by getting it at too extreme an angle.
Rollei in general was very well-thought out and well-executed, but these bellows were simply a dumb idea. It gets even more fun if the fabric has rotted or torn and you need to replace them- arghhhh...