How to implement google ads conversion tracking for ios with flutter

I am running google ads campaign for IOS application , I have implemented firebase analytics in our application ,I have created an event in analytics and imported these events like first_open , screen_view on ads also , I have done all things which is require for ads still I am not getting downloads , In 4 to 5 days we got 444 Impressions , 9 Clicks and 0 install. It is Working fine for android app campaign but it is not working for IOS app campaign. Is there any code issue or we are doing something wrong while running campaign , guys please help me out with this issue.