If this Orange Stage 6 EVO is your bike, the following information pertains to it. One thing that's not listed is if the BB shell is BSA threaded, which I assume it is being an aluminum frame and the fact that many manufacturers have reverted back to treaded shells from press fit. The shell width is the typical mountain bike width of 73mm.
The deal with modern bottom brackets and cranksets are the bottom bracket must be specific to the frame, but also specific to the crankset. The crankset fitment is basically related to the type and size of the spindle. The modern 2 piece cranks that require external BB's generally have 24mm or 30mm spindles attached to one one of the crankarms. The size of the spindle dictates the size of the opening in the bearing ring.
So, we know that you have a 73mm shell and it is most certainly BSA threaded. Whatever BB we select must first of all be compatible with the frame. So, a BSA threaded BB for a 73mm shell, in this case. Since we also need the BB to accept the new crankset, we'll need to know the crankset we intend to use. If we were to select a Shimano crankset, it will have a 24mm spindle and requires a BB with external bearings with a 24mm bore. So now, we need a BSA threaded BB for a 73mm shell and external bearings with a 24mm bore. One could also say, a BSA threaded BB of the Shimano Hollowtech2 standard. That statement has enough info for a bike supply store to obtain the correct one.
Obviously, you are not limited to Shimano. SRAM has a few different standards like DUB (29mm spindle) and GXP (24mm drive side 22mm nondrive side). Other manufacturers make cranksets with 30mm spindles. At any rate, all these crankset standards have a specific BSA threaded BB that work with them. As you may see, the first thing you need to determine is what specific crankset you'd like to use, then obtain the specific BSA threaded BB that accepts that crankset.
Keep in mind that you can also use a square taper crankset or splined interface crankset (Octalink or ISIS), but these cranksets utilize combined spindle + cartridge bearings together in a shell. These "sealed cartridge bearings" come in a BSA threaded option for 73mm shells. Again the length and type of spindle (square taper or splined), which is contained in the cartridge BB, is specific to the crankset. So, again, you must start with what crankset you want to use and then find the appropriate BSA threaded cartridge BB for the crankset.
One final note. You will encounter the same model of crankset offered in BOOST or non boost. If the above linked bike is your model, you have a 148mm boost rear end. While a standard crankset will work, it might be best to get a BOOST crankset as it will give you more options for sizes of chainrings you can use. A boost crankset will afford more frame clearance for the chainring. If you have a 12 speed rear drivetrain, than a boost crankset is required because the tolerances are so tight, the appropriate chainline needs to be adhered to so that you don't get any chain rub at the extreme ends of the cassette.
Wolftooth has published an excellent article on boost spacing and chainline. I encourage you to read this quick and informative article. It also has links to delve deeper into chainline.
