var sqlConnection = new SqlConnection("ConnectionString");
var ssis = new IntegrationServices(sqlConnection); // Error on this line of code
var catalog = ssis.Catalogs["CatalogName"];
var folder = catalog.Folders["FolderName"];
var project = folder.Projects["ProjectName"];
var package = project.Packages["PackageName"];

Microsoft.SqlServer.Management.IntegrationServices.dll
Microsoft.SqlServer.Management.Sdk.Sfc.dll
Microsoft.SqlServer.Smo.dll
System.Data.SqlClient.dll // <-- Via nuget

<PackageReference Include="System.Data.SqlClient" Version="4.4.2" />