Framework is not a valid framework

Hi everyone, I am trying to add ironsource framework to my xamarin.ios project.
I have added dll and framework as per the documentation(https://developers.ironsrc.com/ironsource-mobile/xamarin/get-started-ironsource-xamarin-plugin-ios/). While building the project it says

'Native References/IronSource.framework/IronSource' is not a valid framework. Stock.iOS

I have searched how to add framework to ios project and I have added --mono:framework to my additional mtouch argument (according to Microsoft docs https://docs.microsoft.com/en-us/xamarin/cross-platform/macios/native-references )

This is the output

3> /Library/Frameworks/Xamarin.iOS.framework/Versions/Current/bin/mtouch @/Users/alim/Library/Caches/Xamarin/mtbs/builds/Stock.iOS/35ae000f376de9e87dbe72b91cd5610c/obj/iPhoneSimulator/Debug/response-file.rsp --mono:framework "--gcc_flags=-Xlinker -sectcreate -Xlinker __TEXT -Xlinker __entitlements -Xlinker /Users/alim/Library/Caches/Xamarin/mtbs/builds/Stock.iOS/35ae000f376de9e87dbe72b91cd5610c/obj/iPhoneSimulator/Debug/Entitlements.xcent"
3>D:\Program Files (x86)\Microsoft Visual Studio\2019\Community\MSBuild\Xamarin\iOS\Xamarin.iOS.Common.targets(845,3): warning : warning: ignoring file Native References/IronSource.framework/IronSource, building for iOS Simulator-i386 but attempting to link with file built for unknown-unsupported file format ( 0x56 0x65 0x72 0x73 0x69 0x6F 0x6E 0x73 0x2F 0x43 0x75 0x72 0x72 0x65 0x6E 0x74 )
3>D:\Program Files (x86)\Microsoft Visual Studio\2019\Community\MSBuild\Xamarin\iOS\Xamarin.iOS.Common.targets(845,3): warning : warning: ignoring file Native References/IronSource.framework/IronSource, building for iOS Simulator-x86_64 but attempting to link with file built for unknown-unsupported file format ( 0x56 0x65 0x72 0x73 0x69 0x6F 0x6E 0x73 0x2F 0x43 0x75 0x72 0x72 0x65 0x6E 0x74 )
3>D:\Program Files (x86)\Microsoft Visual Studio\2019\Community\MSBuild\Xamarin\iOS\Xamarin.iOS.Common.targets(845,3): error MT0140: File 'Native References/IronSource.framework/IronSource' is not a valid framework.