2.4 or 5.0, is it selectable? RBR50, Camera will not work with 5.0 only 2.4.

No.  This topic has been explored extensively.  The Orbi broadcasts one WiFi name (SSID) on both 2.4G and 5G channels.  A device that is "only 2.4G", such as many cameras, smart plugs, microwaves, garage door openers, etc. simply is unaware of the 5G channel.  It has no 5G radio.  It is only capable of 2.4G.  Companies warn in BIG LETTERS "must have 2.4G" in the slim chance that someone will try to install the product where there is only 5G, and of course it cannot function in that environment.

The vast majority of products work just fine with Orbi.  Follow the installation directions, provide the Orbi WiFi name and password, and "Voila", product works!  There are some products which have poorly written software, and owners of "mesh" networks such as Orbi, Linksys, and Google, have to do workarounds to get the product working correctly.

If the setup fails, please let us know which product it is and people will be happy to offer suggestions.