The official button layout (for a 2 person cab) is:
Player 1 side Player 2 side
7 8 9 A B C 7 8 9 A B C
4 5 6 D Q S S 4 5 6 D Q
1 2 3 1 2 3
Where D is shield, Q is quick action, S is start, and numbers are the joystick.
Note that MBAC PC has a 6th button, which works like Q but doesn't activate heat and I'm not sure if it dodges. I don't even know if there's any players that use it, but it's there in MBAC PC and not in any arcade versions of MBAC or MBAA.
EDIT: You should probably learn some macros anyways, even if you have trouble hitting 2 buttons at once. It's not only the functions that Q replace that have important macros. Q mainly just makes throws more accurate and there's no reason to not use Q for dodges. Holding 1 or 4 and mashing A+B+C (just B+C works in MBAC but I think you need all 3 buttons in MBAA) is the safe way to wakeup heat. If you just mash Q, then there's a chance it's not timed right, and you get hit before the heat starts. If you're holding 1/4 to block and you mistime A+B+C, you'll just block and nothing will happen. And if you hold 1/4 and mash Q, you'll attempt to throw and probably get counterhit. 6 A+B is also really useful because it's faster to hit 2 buttons than it is to double tap the stick for some things that require a fast dash (it can help speed up instant air dashes is the main use, also it keeps your directional influence in the air to a minimum for more accurate air backdash and prevents you from accidentally jumping or something). It's also much faster to do baits where you dash in to provoke a poke/heat and dash back out when you use A+B, at least in my experience. Manually I can do it fast enough to backdash most of the way through a forward dash (for someone like Kouma). By doing 6 A+B 4 A+B, the backdash cuts the forward dash off at probably less than 1/3 distance.