No offense intended or taken. As someone else mentioned, some folks have unknowingly bought fakes, and I noticed it and pointed it out. I am making some assumptions, but you seemed like a "noob" to this stuff, and it seemed like a good thing to point out in the interest of maybe saving an unfamiliar person from trying to sort out shit gear, thinking its GTG. I am sorry it has derailed your thread.
As for the holster, I'd return it if you can, and buy from a more well known holster maker specializing in RMR compatible holsters. I really like JM Custom Kydex myself, but there are many other makers that are good too (Dark Star Gear, Keepers Concealment etc). Kydex is pretty easy to modify, but its also easy to screw it up, so if you DIY you may end up with a poor plastic pistol shaped paperweight.
ETA: Two things strike me about the holster you have: The belt clip and mounting holes place the lens of the optic right at the belt line, which isn't ideal... Or BELOW the belt line, if you use the upper hole in the front to cant the holster. This is a sign of a poorly thought out design, when it comes to optic compatible holsters, IMHO. It looks like a normal holster designed around a gun with no optic, that had the top hacked down to fit the optic, with no thought to where the optic would end up, particularly if you used the holes that gave the holster a forward cant.