Tcl's http accesses https pages just fine, provided you follow the
directions in the http man page:
https://www.tcl.tk/man/tcl8.6/TclCmd/http.htm
::http::register proto port command
This procedure allows one to provide custom HTTP transport types
such as HTTPS, by registering a prefix, the default port, and the
command to execute to create the Tcl channel. E.g.:
package require http
package require tls
::http::register https 443 ::tls::socket
set token [::http::geturl
https://my.secure.site/]
You don't say if you did, or did not, follow these directions above, so
until you let us know if you've registered an https handler with the
http module, there is little more we can do here on Usenet to help.