Office 365 - Add Shared Mailbox's Calendar to mobile device

With all the recent changes to Office 365 I found that it's become confusing as to how to easily add a Shared Mailbox OR Room Calendar to a users mobile device.  This works for both Native iOS calendar app or the Outlook for iOS / Android app.

This post goes over the new features
Calendar Sharing in Office 365

Additionally, this post goes over sharing your calendar!
Share your calendar in Outlook on the web for business

And finally, this has instructions for opening a shared mailbox in a seperate window so that you can access the necessary share button which is critical step.
Open and use a shared mailbox in Outlook Web App

Natively, when you create a new Shared or Room mailbox and assign delegates from the O365 Admin portal the new mailboxes / calendars will automatically show up in your Outlook for PC application after a short period.  They do not however automatically show up on your mobile device.  Instead, you must access the Shared / Room mailbox directly and add each user as a delegate which in turn emails an invitation to the users.  The user must then accept the invite from the mobile device which will add it to all of their mobile devices.

1. First, we've created the Shared mailbox we want and added the "members".  This will automatically add the mailbox / calendar to those users Outlook for PC application. 
   
2. Log into OWA with an account that has permission to the Shared Mailbox / Room that was just created.  Click the user account in the top right corner.  Click the "Open another mailbox..." option.
   
   
   
3. Type in the name of the mailbox / room and ensure it finds it in the list.  If you don't have the proper permissions then you'll get an error "Something went wrong".  It can take some time after assigning permissions to yourself before they properly propagate.
4. The mailbox will open in a new window.  Open the calendar.
5. Click the Share button at the top middle.  This will open up the "Share this calendar:Calendar" window.
6. Search for the person you want to add and give them the proper permission level.  Then click "Share"
   
7. This will send an email invitation to the user. They will need to open the email invitation from a mobile device!
   
   
   
8. From iOS native app the calendar is listed.
   
9. Or from the Outlook for iOS / Android
   
10. If the user wants to remove the calendar they can click on the i / information option on the right side (iOS) or settings gear (Outlook for iOS / Android) and at the bottom is the remove option.

Hopefully MS will give the option of having these calendars auto deploy to mobile device same or similar to the way it does with outlook for PC in the future.