Yep, that's all working for me. GOOD FIND btw, so maximum thanks for sharing 🙂
I ignored their instructions and put the files where they should be, which in my case (PC) was /users/your login/appData/Roaming/MAXON/RXXXX/Plugins/LWcad R21.
(the folder in gold I had to create myself). After restart of Cinema, it should appear at the bottom of extensions menu, and does for me.
CBR