Hello there!
Second day Macbook user here. I tried installing VCMI (latest build) and the the fullest Heroes 3 version without mods. I downloaded the essentials pack and if I choose any other error then 800x600 I get this message:
abort() called
terminating with uncaught exception of type std::runtime_error: Requested screen resolution is not available
Other than that, the game seems to be working ok with default resolution. Where the problem can be?
You must download and unpack in main folder VCMI essential files from here: https://wiki.vcmi.eu/Mod_list#Utilities
Pack contains additional resolutions and random maps templates