Only allow public contributions from guest users in Omeka S?

Hi there,
I’m working in Omeka S, and would like to limit public contributions to people who have created a guest user account only. This seems quite well documented and explained for Omeka Classic, but I am having trouble working out how to do it in Omeka S.

I have downloaded and installed the following modules:
Collecting version 1.7. by Omeka Team](https://omeka.org/)
Guest version 3.4.15.3 by Daniel Berthereau

I can see how to add a ‘register’ and ‘login’ page to the navigation bar, but what I’d like to do is limit access to the contribution forms to guest users only. This website (built using Omeka Classic I think?) is a great example of what we’d like to do: https://baltimoreuprising2015.org/contribution

Here is the link to our test site: Welcome · Test - LHE Archives · Legalhistemp

Many thanks!!
Rachel

**Update: have also tried the 'RestrictedSite (v 2.1) module, but this seems to apply to the entire site, not just specific pages. RoleBasedNativation (v1.1) is almost what we are looking for, but only seems to limit the links displayed in the navigation bar by user role, rather than actually permitting access to the collecting forms.