I have installed flutter and need to add it to my app because I want one of it's features, and also have added a new flutter module to my app, now how should I change the existing libraries(ex: implementation 'de.hdodenhof:circleimageview:3.1.0') so that they are compatible with flutter, as in how do make my existing app fully compatible with flutter?
What do you mean by making your existing app fully compatible with Flutter ? If you successfully created a Flutter module and import it in your application, then you are able to launch an activity and display UI thanks to the Flutter engine. The library you mentioned in your post has its equivalent in a basic Material Flutter application and its called a CircleAvatar.