What I’ve been using for years:
If you have a spare Fleshlight case, cut where you see the red lines. Then heat up the two bends one at a time to soften the plastic and straighten the arms.
Use rubber bands to secure the sleeve inside the arms. Will attach to anything capable of holding a Fleshlight case, and will hold any sleeve that physically fits inside. If you go this route, get a good sized bag of rubber bands, because contact with the sleeve material will degrade the rubber over time - it gets bloated and weak.
The sleeve you linked seems to be on the large size, but it might be OK.