Restricted content page template

You can style the plugin’s forms with CSS. There is more information on stylesheets here:
https://rocketgeek.com/plugins/wp-members/docs/customizing-forms/

Also, every piece of the form building process goes through at least one filter. If you need to change HTML in the forms (to add/remove classes, IDs, div/span wrappers, and other HTML), you can filter those to handle whatever HTML you need.

In some cases, there are default wrappers defined, such as wpmem_register_form_args:
https://rocketgeek.com/plugins/wp-members/docs/filter-hooks/wpmem_register_form_args/

But you can also filter after the HTML is applied with wpmem_register_form_rows and/or wpmem_register_form:
https://rocketgeek.com/plugins/wp-members/docs/filter-hooks/wpmem_register_form_rows/
https://rocketgeek.com/plugins/wp-members/docs/filter-hooks/wpmem_register_form/

These are just examples; there are others.
https://rocketgeek.com/plugins/wp-members/docs/filter-hooks/

How do I not show the Registration Form when the user is not logged in to the site?

I would just like to show the message and the login form.

[ ]’s Robison