installation – Problem in installing Matex

I am using Mathematica 12.0, and I want to install Matex. According to this page

only writing the code ResourceFunction["MaTeXInstall"][] should work, but I get this error

enter image description here

I have downloaded “MaTeX-1.7.8.paclet” and put it in drive C, but the problem still persists.

Can someone please guide me where I am going wrong? I am not good at installing software and so on, maybe it is so simple.