How to include a public html ressource in a protected web app?

For my test project (build a teams tab app with a bot), I need to serve a public web page to config the tab.

I created a localfile mstConfig.html and embedded it into a browser widget on a form frmConfig.

I need the URL of this content for the configuration of the teams tab:

How can I add this web ressource to my app so that it can be addressed publicly?