env. file link does not seem to be working?

Hi - I am trying to extract text from a miro mind map file if it is coloured #f22626 (red) and send to a google sheet...and came across this posting.
I'm having trouble getting the Miro app to work - what is a env. file and what is npm start?

I am not a developer, but a teacher who would really like to get my app up and running!

Any help or suggestions would be awesome!
kind regards
Matt