I did the Exodus trip (Atlas Descent) a couple of years ago.
I know that they do have bikes based in Agadir as a couple of the guys on our holiday used them, but I have no idea if they would just rent the bikes out. TBH the organisation was a bit shonky, with a UK guide who didn't really rate Exodus, although the local guides were great.
The holiday was amazing - just for the scenery. We didn't ride from Agadir, but rode back down to the coast to the North of the city, from the high Atlas mountains, at the end of the trip. The trails that we rode were all small roads / donkey tracks. The area is very agricultural and single track paths were few and far between as a very sparse covering of short wheat is grown on any available spot. Riding off road would likely wipe out the families daily grain ration in one easy swoosh.
As Mostly Balanced said the rough roads and trails inevitable lead to a group of houses with kids showing a great interest in your bike. We didn't come across any malice of any sort, but you do feel a bit of an arse when you are riding a bike which (possibly) cost more than they earn in a year
If you can find a bike and are happy just exploring the back roads and villages then I would go for it, if you are looking for techy singletrack then you would need a guide... although if you are lucky you may find some lovely grippy rock slabs to play 'chicken' on