Haven't used Quixel in years, a few questions.

Last time I used Quixel it was basically a plug-in for photoshop (nDo, dDo, 3do.)

1.) Has this software been replaced with Mixer or is Mixer an alternative program?I
2.) For pricing, I noticed that there's only one option and that's Megascans but nothing for Mixer. Is Mixer itself free but Megascans a subscription based service, or is it that in order to use any of the software you must have a Megascans subscription?