I've spent over 3 hours on this, reloaded a few times, no luck. I can't get the Stablized Reflector Platform to snap with the Molecular Beam Emitter at Sanctuary (in multiple different locations). I've watched so many videos on youtube seeing if there was a trick to this, but it doesn't appear to be, it just doesn't want to snap. Any suggestions?

You don't have the platform on a floor tile do you? It has to be on the ground. I made the mistake of constructing a giant wall to surround it thinking I'd get to use it more than once, but whoever's helping you build it should notify you that it only goes one way, one time.

That worked. Thanks.