Good news! I was able to find the problem.
As those who have been following this saga know, I installed a new instance of WebsiteBaker with version 2.12.1. It is in a directory named testing, and the server has the following directory structure:
/public_html (where 2.10 is working)
/testing (where I want to put 2.12)
First of all, when I open the site at https://testing.greenmaking.com
it shows the WB "Website Under Construction" message (after you click through the security warnings and add a security exception).
I had a problem with an undefined function, but the ISP loaded the library for it and this went away.
However, when I try to log in as admin it would say, "Login name or password incorrect".
I tried the "Forgot Password?" link twice. In each case it sends me an e-mail message that says (in part):
Your new 'Green Making' login details are:
Login name: xxxxx
Your password has been reset to the one above.
It actually sends "xxxxx" for the login name, but I take that to mean "admin". It gives me a temporary password for "...". However, using that password for admin in the Login dialog box failed.
I believe the forgotten password process is updating the right database because the value in the wb_users.password field for the admin user changes when I go through the process.
I checked the logs for the site. I have two: install.log.php and php_error.log.php.
The first line of install.log.php is a PHP line designed to stop this file from being executed. After that it shows that config.php was successfully written. There are a bunch of install messages. Then it says, "Couldn't remove config.php.new". But the final line says:
Installation successfully at Fri, 18 Jan 2019 22:14:31 +0000
I checked and the config.php file it generated looks correct, as far as the DB lines go. However, the file ends with:
The other file, php_error.log.php, just has the <?php die
line. So, it is not reporting any errors.
However, in looking at this, I realized that the define for WB_URL is incorrect. It needs to be 'https://testing.greenmaking.com
I may have entered it wrong in the install. It may be that the install script regularizes this to "http". If so, that should be corrected in the script, but it's more likely I just mis-typed it.
In any case, I changed this line in config.php and now I can log into the administrator.
Thanks for your help and support!