** Using WeBWorK **

For the most part, everything that you have done sounds like it will work, except the certificates obviously (obvious because it isn't working).

I assume you are trying the direct deployment approach (not proxying via apache2 or nginx).  If that is the case, rather than installing apache2 to get a user to work with you could just create a user.  You should look at the webwork2/conf/README.md file.  It has instructions on how to do this, and some other information you might find useful.  To create a user you run "sudo useradd -M webwork" (or use apache if you like instead of webwork).  You will need to edit the service files to change the user name.

At this point stick with node 16.  Node 18 probably will work, but it is untested with webwork2.  If you do test it, then report back on how it goes.

As to the authbind package not being available, what you have done should work.  Although you should see https://github.com/openwebwork/webwork2/pull/1874.  That changes this.  Instead of using authbind it switches to using the Mojolicious::Plugin::SetUserGroup module.

As to the certificates, I have never actually been able to get self signed certificates to work on a real server even with apache2 or nginx.  I have been able to get them to work locally, but not for a remotely accessed server.  I don't think that self signed certificates are actually supported for that.  You could try letsencrypt with certbot.  That is something that is free and does work.

The self signed certificate may not be the issue though.  Another possibility is permissions.  Make sure that the user you are using has read permission of the certificate files and any directory leading up to them in their path.