To specify which spreadsheet to send to, simply enter the sheet ID in the url. (EX: team5419.github.io/scanner/?id=sampleidhere)
Link
Setup identification variable for Google API by clicking the link.
Link
For Node: make sure bore are allowed to run on site (team5419.github.org).
You can do that at the link below.
You must create a new client id if its not configure to work for web application.
Link