Sorry to say this but I wouldn't turn that machine lose on an expensive piece of hardwood because there's a high chance it will wreck it.
Like someone else lower down says it won't last very long and will soon become baggier than Grandads Y fronts.!!

The fact it use's plastic rollers in profile slot ensures it's doomed from day one, those rollers are meant for sliding doors not CNC machines.

The Z axis will bend like a banana with only slightest cutting forces and will flex badly giving a very poor finish in any thing harder than Balsa wood.

If it's possible to return then I suggest you do so ASAP because it's completely inappropriate for cutting guitars.

If you do keep it then Don't buy the Am882 has they are completely OTT for this small machine.
This will be much better suited, still uses digital drives that are rated to 60V and comes complete with built in breakout board and Spindle speed control, thou this won't control Kress speed but will turn ON/OFF.!. . . . Just add power and your good to go.
MX3660 - 3-Axis DSP Based Digital Stepper Drive Max 60 VDC / 6.0A

Sorry to be Negative about your new purchase but it's a lemon for any decent quality work.