the angle unit needs clearer marketing- it is really for transfer of angles, as mentioned above, and it does this well. not great for lots of repeat 90 degree cuts we typically do all day long. i suggest looking up Guido Henn's videos. in one of them he has a simple homemade 90 degree cutting setup. its just a panel to hold material, with a front/rear feature to hold the rail. i don't keep track of his videos so i don't have a link, but perhaps someone here who is more on top of things can remember??
there is also the mft, of course, but if the budget does not allow, as mine did not at one point, a home made unit works well for very cheap.
another setup is buying a mft replacement top, around $50-175, depending on size, and putting a little base on it to lift it off the floor/table a bit, and using qwas dogs or similar product to set the rail to 90.