To setup a development environment, first check that you have dependencies of PowerShell 5+ and choco installed.
Then copy the personal packages template to a file called personal-packages-testing.xml so as to be able to use the .vscode/launch.json settings.
Adjust the options in personal-packages-testing.xml as needed for what you are testing.
Unless you are working on RepoCheck code, I would suggest skipping (or disabling) it so you don't get rate limited or a temporary IP ban.
See code formatting from the settings in .vscode/settings.json. It's not a big deal if your formatting is slightly different, I'll just correct it afterwards.