Usually a documented ITIL process is required such as raising a Service Request via the Helpdesk to request a Shared mailbox, or to be given Access.
Sometimes there might even be a front-end style Portal to achieve this. This can ONLY be granted by an Exchange Administrator either at the Exchange Management Console / Exchange Admin Center or via Power Shell.
Outlook's Auto Archive feature automatically archives data at specified intervals.
If meetings aren't displaying on your calendar, they may have inadvertently been archived.
The longer the refresh rate, the less up-to-date your calendar will be.
Click the "Today" button in the Go To group, click the "View" tab, then click "Reset View." Click "Yes" to confirm.
Click "File," click "Account Settings" and then click "Account Settings" again. Re-enter your password under the Login Information heading to ensure Outlook is using the correct password.
Also double-check that the information displayed in the Server Information section is correct.
In a very small, or even small/medium organisation, often these decisions are very straightforward.
More often than not users are in close proximity or on first name basis with the IT Teams but for a larger or Enterprise size Organisation this is simply not practical.