You don't need to use node-red-admin
cd ~/.node-red
npm install node-red-contrib-mssql-plus@n.n.n
where n.n.n is the version you want to install.
You don't need to use node-red-admin
cd ~/.node-red
npm install node-red-contrib-mssql-plus@n.n.n
where n.n.n is the version you want to install.