I'm assuming windows. It's helpful to use console but not necessary:
Go to steam -> Library -> find Zero-K -> right click -> Properties -> Local Files -> Browse Local Files, it opens Zero-K directory.
Go to engine -> *your architecture and os, presumably win64* -> *latest engine version, probably 104+* -> run spring.exe
Then select game mod (scroll to the bottom for latest Zero-K 1.6+
Then search for your map - it should list as "*mapname + version*" specified in mapinfo.lua you should provide with the map files in map directory. If you didn't specify it, it should be your smf file *name*. If it does not list, make sure you've put it in the right place or search wiki where to put it. I am not certain whether steam directory is the right place to put it or there's some external place like in %APPDATA% - someone more knowledgeable could clarify that. I'm sure it searches in many places if that's the case so it shouldn't be a problem.
Then you are left to select scenario for testing - Null AI exists for this purpose.
Then all you've got to do is press "Test the game". Your choices should save when you shut down engine, so it's not very meticulous to set this up every time to test, but I recommend in the future when it gets tiresome to use command console - then you can prepare one-liner which will run all settings properly and start the game right away without clicking. The most important use of console is extra feedback that it gives on standard output about some warnings and errors you might have made in your map (especially scripts).