My question (same as the last post of the linked topic) remains. What did adding "-L. -lcurl" do so that code could now successfully compile? I would like to understand the meaning, process, and hopefully avoid similar issues in future.
Depending on how your system is set up you might not need -L. Try it without.
-L. adds the current directory to the library search path. In your other post you stated that you copied libcurl.dll to the project folder so I figured that would work.