Is the wording 'Install as app' on all pages on edge? Other browsers show 'Install as app' only for PWA and 'add to home screen' for normal websites.
Edge doesn't show 'Install as app' in address bar but if you go to menu > apps there will be 'Install this site as an app'. I'm using apps for Duolingo, Ventusky, Airly, Livescore, Plaza One, Poolside FM. I even tried to make an app for this website and it worked.