You may not be able to set this in the properties pane on the right, but if you double-click on an empty spot on the page or right-click there and click properties, you should still be able to set it. This is a known issue that should be fixed in one of the upcoming releases.
Do you have user roles allready? and did you also set the module roles for those users? You can click on app > security, then go to the tab user roles, if you have a user role click on it and then set the module roles.
It is read-only under Page/Properties, but once you add it to the navigation and assign roles to that page in security, then it gives you information on who can see that page...