The integration through Fabric is very easy and straightforward.
Please follow the instructions in the appropriate link:
For iOS: You need to set the right API key on the Info.plist file, fabric -> kits -> appsee
The initiation call is: Fabric.with([Appsee.self])
Note: When integrating iOS with Fabric, please make sure to only use Fabric.with() without using Appsee.start().