That sounds like what you would get booking an “accessible room with tub” - which is a booking category not a request. Are there no accessible rooms available?
They may be able to honor the requests, but if you really need those items to make the tub/shower accessible to you, I highly recommend booking what you need and not relying on a request. I’ve read differing reports about getting a handheld shower installed, and the bench may or may not be what you need or in good condition. I’m not sure I’ve heard of anyone getting grab bars installed - those suction cup ones work until they don’t, and can’t be installed on small tile or texture surfaces. Requests are not guaranteed - especially when the request can granted via a bookable category. I would look into booking an accessible room.
Enjoy your vacation!