Can't add certain package to my app

Hey guys,

I am trying to add the Stripe package to my Xamarin.forms app but I am getting this error message:

Could not install package 'RestSharp 105.0.1'. You are trying to install this package into a project that targets 'portable-net45+win+wp80+MonoTouch10+MonoAndroid10+xamarinmac20+xamarinios10', but the package does not contain any assembly references or content files that are compatible with that framework. For more information, contact the package author.

I read in several forums that this might be because of my NuGet version but I don't know how to manually update it, if this is really the problem ..

Thanks in advance !