5. If you get error 500 this means that there should be an error written out to your PHP logs. Alternatively, you could enable WordPress debugging and see the error in your debug.log. If you can spot this error, please share it with me so I can help you.
In any case, it seems from your screenshots that the plugin fails to read information about the installed extensions. This should happen only when you attempt to view the Dashboard section. Not sure about the exact reason but I could add some guard code to make this fail gracefully.
Do you see a problem when you visit any other page in your admin interface?