To add the pro module frameworks, you need to sponsor the project on either Patreon or Github Sponsors. See:
Once that's done, download ChatSDKPro and ChatSDKPro.podspec from:
Add them to your project. Then add the modules to your Podfile:
pod "ChatSDKPro/ContactBook", :path => "../"
pod "ChatSDKPro/Encryption", :path => "../"
pod "ChatSDKPro/Firebase", :path => "../"
pod "ChatSDKPro/FirebaseNearbyUsers", :path => "../"
pod "ChatSDKPro/Message", :path => "../"
pod "ChatSDKPro/ChatK!t", :path => "../"
Just add modules you are licensed to use.
Replace the :path parameter with the path to the ChatSDKPro.podspec file.