Opening HTML file to operate Firebase on MIT App Inventor

MIT App Inventor Help
1

Hello!
I'm making an app on MIT App Inventor with a login page. I created the login page and buttons using an HTML file and coded the buttons using MIT App Inventor (following this code http://appinventor.mit.edu/explore/ai2/firebase).
However, whenever I try to open the HTML file on MIT App Inventor, an error comes up saying "ERR: FILE_NOT_FOUND." The file is uploaded like this:
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Is there any way to fix this error? My code is uploaded below. Thank you!

code
code1483×768 160 KB

2

Try with:

http://localhost/FirebaseAuthentication.html

(should work with development and compiled, if html file is in assets)