A wonderful combination of incompatibility, you might need to get yourself a windows operating system for War3, it would save you much headache.
Warcraft 3 Reforged is supposed to be compatible with windows 7/10 and 11 alongside Linux and MAC but in practice the development team show they care little for anything other than the latest windows machine.
If you want to get something cheap together i suggest getting an old second hand laptop with windows 10 and download the portable version of Warcraft 3 patch 1.31.1 from the
Hive Archives under Game Files tab.
If you aim for a slightly more powerful second hand laptop you can run Reforged on it, preferably one with a laptop mobile 1060 or above GPU. It will still not be optimal as RF itself is resource heavy but it should be more than enough for classic graphics.
Technically, you can even hunt for a mini PC instead which would allow you to focus your budget on the specs without losing money on buying a display, and then just use your Macs display instead, assuming your Mac is a laptop and not itself a mini PC.