Ionic 3 Firebase Crashlytics

I have developed app ionic 3 .so i want to intergrade firebase crashletics. in ionic V3

$ ionic cordova plugin add cordova-fabric-plugin --variable FABRIC_API_KEY=XXX --variable FABRIC_API_SECRET=xxx
$ npm install --save @ionic-native/fabric@4

but currently can register and create fabric account and i cant get FABRIC_API_KEY
so how can intergrate it ionic 3

also i have tried

ionic cordova plugin add cordova-plugin-firebase-crashlytics
npm install @ionic-native/firebase-crashlytics

could you please help.