how can I read out the Firebase Instance Id ?
You can use getFirebaseDeviceToken() function as mentioned on the below docs link:
Thank you but I already know that but you firmly refuse to tell us users what we should do with it.
There are also users who cannot program!
What is the entry: Website2APK?
does that have to replace with my app name?
Where should it be installed?
In Builder I have no options and somehow something is missing from all the script calls ???
Are these just links for buttons or something similar?
That doesn't work.
Please explain in more detail in the doc, so there is no need for constant inquiries.
What is the call or how?
You need to have basic knowledge of JS to get it right. Let's see.
var token = Website2APK.getFirebaseDeviceToken();
When you write above code as mentioned in documentation. the variable token now gets assigned the value of your firebase token string. You can now use 'token' anywhere in your web application. It is as simple as that if you know JS.