Run the app builder locally
Open the file Builder/firebase_config.js.
Here you should enter the firebase connection string.
There enter your admin email, purchase code etc..
Using Terminal or Command Prompt navigate to the downloaded and extracted zip. Then navigate to the folder "Builder"
npm run start
This will start your project on localhost. You will get the correct link. Probably
After you have run the builder locally, and if it works ok you can easily publish it on your own hosting if you want.
npm run build
This command will make a dist folder.
Upload this dist folder to your hosting.