All right. He send me his website from PM. But I will share the solution from here maybe other people will have some problem in future.. Well when I open developer tools I see you don't have manifest. You've set it from admincp but it doesn't added webmanifest to your page so...
open PAGE_CONTAINER template and inside <head> </head> tags add the following code:
<link rel="manifest" href="/webmanifest.php">
After then wait a bit and clear cache, you are good to go.