If you need to make a Space or Page available to the public
Confluence offers "anonymous access" which means the site visitor does not need to login to view Confluence content. You will need Space Admin privileges in order to set permissions
Step-by-step guide
Determine if you want public access at the Space or Page level
To make a Space publicly available:
Confirm with all editors that no Confidential, Sensitive or Internal Data will be stored on the site
Access Space tools, scroll to the bottom to see Anonymous Access, and select Edit Permissions
Select All → View and Comments → Add if needed, and select Save All
Confirm that only View and Add Comments permission have been selected
If you want the Public to only see one or more pages in a Space, you will need to give the public Space permissions to the space, and then use Page Restrictions to restrict access to pages that you do not want the public to view.
Add the individuals/groups that you want to view/edit the page(s). If the public has View access to the space, they will no longer be able to view content on pages that have been restricted to certain users or groups