There is no information I can find on the Chain Reaction Cycle page that indicates what bottom bracket standard the crank requires. Seems the crank was originally sold with a Race Face bottom bracket and that bottom bracket was heavily implied (through the product images) to fit an ISO/BSA threaded frame of either 68 or 73mm shell width.
I checked the Race Face website and cannot find a product that is obviously the same. At least a few of their cheaper cranks are specified as having a 24mm axle. That definitely will not fit in a SRAM GXP bottom bracket as those are 24mm on the drive side, 22mm on the non drive side.
If you definitely want this crank to fit, buy a Race Face BSA bottom bracket as well, that will fit your frame and the crank will fit the bottom bracket.
It looks like the the Race Face BSA bottom bracket is the same dimensions as a Shimano HollowTech II bottom bracket, so you could try one of those, but I cannot absolutely guarantee it will work (there may be some variation in total width).