Sorry, had to wait 30 minutes between every post.
But yes, everything is in same folder, alpha-preview-1.0, all the files mentioned, plus some more microsoftAPIcodepacks.
I'm on Windows 7 if that matters, and tried running the application as admin as well. Loads fine, and it sees every save game I have, only when I click 'Load' the error message appears.
Even tried to make that folder structure mentioned in message E:\Documents\Visual Studio 2017\... and extracting there, but no change.
From the screenshots, editor looks simple and concise, I really like that.
Great job again!