Np.. I am curious, however. Did you actually try MAST on Unity 2017? I'm almost positive it would work without any issues.
Yes I tried, had to download unitypackage since asset store asks for unity 2019 to allow download.
Then I got errors including "not part of C# 4.0 language" and others "UnityEditor.PrefabUtility' does not contain GetCorrespondingObjectFromSource / SaveAsPrefabAsset".
Could debug some but not the ones including PrefabUtility. I don't ask for help with this, should be resolved wth new up to date computer coming one day :V