It’s helpful to understand there are two main client libraries for Analysis Services. A client library is what you can add to any new Visual Studio Code Project to provide objects, methods and functions relevant for the tool you are building.
Make sure you download the NetCore (.Net Core) versions of these libraries when working with Visual Studio Code. There are .Net Framework versions of these libraries that are more suited to use with the full Visual Studio product.
Read on for links to those libraries and a thorough demonstration.