Just got back from same area, had a brilliant day riding up to the snow line and back :)))
I am a bit of an XC fairy and was riding solo so just stuck to the easy stuff but there looked like there was lots of fun to be had.
A guide to show the way and call for help in case of skill or bike failure is a must if doing anything interesting. If I was going back I would be getting in touch with Ciclomontana.
They pointed me the way to a new bike hire/repair place in Bubion (right in the middle of the MTB zone 10km ish from Orgiva) Alpujarrabikes 0034858857034 (no website!). Might be handy if you don’t fancy paying to fly your bike/shread a tyre/pringle a rim.