please help us with more details,
esp. as you post in a one year old topic.
- what exactly you download
- how unzip
- and start what / how
++ also tell us more about your environment / OS …
example, for a other topic i play
https://editor.p5js.org/kll/sketches/I_NCyfDYR
i select / File / Download /
and save local xxx.zip
- on a WIN 10 PC unzip
- and double click on index.html
and select my firefox browser to run it.