Apps created using v4.0 won't show up any false positive alert.

This icon pattern is due to latest material design guidelines, as you can also see on many other apps. The icon fits between the circle to make it look similar to all others. But one thing that you can do to get some large icon is that you should make your edges rounded and transparent as the outer circle holds inner image with small margin. You simply need to know that if you use rounded icon it will show the biggest possible, you can try out with that.

It seems like your network specific issue, kindly consider checking on some other network.

No need of Android Studio. Simply use google-services.json file in App builder, that's all. Follow the steps and nothing more.
https://websitetoapk.com/docs/fcm-push-integration.html

Yes, you should still follow the link and generate google-services.json file for integration.

You need to integrate google-services.json file for integrating firebase services to the app. PushAdmin is a service to allow you to send notifications to the app.

It represents that an SSL error does exist on your website which can be fixed by fixing ssl certificate on your site.

PHP is not supported for offline apps as it is not possible to run PHP without a server.

If you have already made the integration of google-services.json file through app builder then you can continue to use PushAdmin to send notifications without any issues.

@hermawan It seems that you were trying to upload files on the web and not through the app, so this issue does not relate to website2apk. Still, glad to know you found the solution for it.

@hermawan You need to enable file READ WRITE access to be able to use upload function properly.