Where can I switch on the Access code field?

You can do this on the Settings page. Go to Advanced settings and you will see the following options:

Options

Next to the option Access code you are able to check two boxes. If you select the checkbox Available when logged in then the access code field is available for learners that are logged in. Learners can add an access code on the Home page in order to get access to a new course.

When the checkbox Available when logged out is selected, the access code screen is visible on the login page. This subsequently means that new users have the possibility to create an account first by using an access code.

It is also possible to select both checkboxes. The access code field will then be available for learners that are logged in and for users that aren’t logged in or learners who don’t have an account yet.