You need to debug your app to find the exact issue:
https://websitetoapk.com/docs/debugging-with-chrome.html

There will no problem at all. Apps created are fully compatible with google play.

Not at the moment. We do only have Firebase push notifications support.

What error does it show?

Announcing a new release v5.1 Pro.

Latest API Level 31 Support
Android App Bundle (.aab) Support
Java Dependency Removed
**Bug Fixes

https://websitetoapk.com/download.html

https://forums.websitetoapk.com/332-app-showing-fatal-error/0

@nouen My sincere apologies to you as well in case you are having some troubles, however, we always endeavor to make it easier and everything to work properly as expected by customers.

Further, what I can offer you is that if you can send us your APK files, we can do a check for you and can surely provide you with the required fix and tell where it all goes. It is not just about 'what you pay' , but what out tool works for and what it can actually deliver. So even if you have the free edition, we will still get it working for you. And to be honest, It has nothing to do with software, but we can figure out the issue for you!
Kindly send APK by attaching to support on link below:
https://websitetoapk.com/support/submit_ticket

All of the HTML/CSS/JS should work as it is where it uses relative paths (very obvious). It is just simple thing which does not require any tutorial, it should simply work without doing anything special.

Further, if they don't work, as a web developer, we expect you to understand debugging in the browser, and the same can be performed with the App as well when you build the APK with our tool.

https://websitetoapk.com/docs/debugging-with-chrome.html

Using above link, you can debug and find out the exact issue on the console.

Further, our support can assist you all the way through any problems that you face.
https://websitetoapk.com/support/submit_ticket

Make sure if you have enabled cross-origin ?

Also, to know exact error, you need to check console logs:
https://websitetoapk.com/docs/debugging-with-chrome.html

Alias password and keystore password is same in case you need not enter it. It is optional to use a different password, so it takes by default the password put the in command for both.