ERROR: admin/includes/configure.php file not found. Suggest running zc_install/index.

As instructed in the documentation, I have renamed the admin. But I also wanted to use HTTPS. ATM the admin folder is reachable via the regular path:

http://webshop.mydomain.com/renamedadmin/

Then I copied the renamed admin folder to the httpsdocs. Same name, same relative location. I changed the configure.php in the httpsdocs, so all http became https. I did not set the ENABLE_SSL_ADMIN to true yet (although I have tested with that).

httpS://webshop.mydomain.com/renamedadmin/

As soon as I try to access https, I get the error:

ERROR: admin/includes/configure.php file not found. Suggest running zc_install/index.

I do not understand; why is admin referenced? Because there is no admin only renamedadmin...

Turns out the error is hardcoded in application_top.php as a result for some 'interesting' checks;

die('ERROR: admin/includes/configure.php file not found. Suggest running zc_install/index.php?');

It seems I have to copy the whole tree to both httpdocs and httpsdocs... We'll see.

Copying the whole tree leads to the "To begin installation" page. Better, but not yet.

It might be better to get your hosting company to configure your account so that HTTPS is served from the same directory tree as your HTTP content is.
Otherwise you're going to end up having to keep duplicates of everything, including duplicating all your product images etc anytime you make changes.