After Step 4 when I click allow (step done by your user2, the user trying to open the secondary calendar) I am told:
"Outlook cannot open the folder
You do not have permission to open this folder. Contact <User> for permission."
The calendars never shop up as they do in Step 6. Again the user opening does not have access to the user's main calendar (user who created/shared secondary calendar)
I am on the latest update Office 2011, this works for a shared user on Office 2013.
I may just go with shared mailbox/calendar; this may also work.
Thanks again