How to add RingCentral Nuget for .Net 4.5.2

My current project is on .Net 4.5 and wants to integrate meeting API's. Trying to add SDK but getting

Error: Could not install package 'RingCentral.Net 3.0.0'. You are trying to install this package into a project that targets '.NETFramework, Version=v4.5, 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.

Is there any way that I can add this sdk or any other solution?