A 403 forbidden error is caused by missing credentials. Through current installation methods, there are basically two ways to get the novarc file. The manual method requires getting it from within a project zipfile, and the scripted method just generates novarc out of the project zip file and sources it for you. If you do the manual method through a zip file, then the following novarc alone, you end up losing the creds that are tied to the user you created with nova-manage in the steps before.

When you run nova-api the first time, it generates the certificate authority information, including openssl.cnf. If it gets started out of order, you may not be able to create your zip file. Once your CA information is available, you should be able to go back to nova-manage to create your zipfile.

You may also need to check your proxy settings to see if they are causing problems with the novarc creation.