what does `curl -e` or `curl --referer` mean?
From the man page of cURL
-e, --referer <URL>(HTTP) Sends the "Referrer Page" information to the HTTP server. This can also be set with the -H, --header flag of course. When used with -L, --location you can append ";auto" to the --referer URL to make curl automatically set the previous URL when it follows a Location: header. The ";auto" string can be used alone, even if you don't set an initial --referer.
Essentially this tells the server which page sent you there.