Not really.
It is initiated by web page. They prepared "manifest" file: https://freebitco.in/manifest.json which defines icons and label for proposed link.
Then that file is served to client with that piece of code in the page source:

All together causes mobile browser to propose link creation.
Behavior is described here: https://developer.mozilla.org/en-US/docs/Web/Progressive_web_apps/Add_to_home_screen