In the top level ngspice folder there are two compile scripts compile_min.sh and compile_linux.sh. They contain information how to compile ngspice with ADMS. You will have to run autogen.sh with the adms flag

./autogen.sh - -adms

In addition you have to add - -enable-adms to the ./configure command. Please check 32.1 for perequisites and further details.

Compiling ngspice with ADMS with MS Visual Studio is not supported.