There is a bug in the CompileAndLoadTargetAssembly in UAT. It always attempts to create a dummy TargetInfo using Win64 as the target platform. I’ll change that to check the host platform and utilize that, but in the mean time, if you have source, in ProjectUtils.cs at around line 486 (may be different line in 4.7.5) there is new TargetInfo(UnrealTargetPlatform.Win64 change that to UnrealTargetPlatform.Mac and you should be ok to build until I get the fix in.
-Pete