Hi David,
For the wrong file type just do the following:
1. Right click the file and select “Open With”
2. Check the box to say always open with selected program
3. Navigate to any metaeditor.exe file and all should be well
Let me know how it goes.
I trade my own Robots so am currently unfamiliar with Petkos process, I will review and get back to you. Usually I personally just use the same EAs that passed the challenge but lower the risk to about 70% of what I used for the challenge.