Hi Swapnil,
Please confirm the following:
1) You have set up the configuration files according to the configuration guide. The zip folder can only contain the google-services.json and the GoogleService-Info.plist. These files can't be in a subfolder of the zip.
2) The application is correctly generated. For that the app identifier needs to match the one you used in the Firebase console.
3) The setup in the Firebase console is done properly. For this you need to generate a p8 file from the Apple Developer portal and upload it and also insert the correct key ID and team ID.

I've followed the above steps when configuring all iOS apps and I can receive push notifications.
Looking forward for your answer.
David