I'm using Office 365 but I seem unable to share and sync my mail, calendar and contact items between multiple computers even though I'm allowed to install it on up to 5 devices.
I was told that Office 365 was "Cloud Based" and I’m signed in with my Microsoft Account to Office, so shouldn't I be able to do this?
Well, not necessarily. It depends on whether you are talking about Office 365 for Home or Office 365 for Business.
Both are “Cloud Based” but both in a different form.
Office 365 for Home
Office 365 for Home isn't “Cloud Storage” but “Cloud Based Software Delivery” or “Software as a Service”. This subscription based service delivers, installs and updates the latest version of the Office Suite via the Internet via a special streaming method also known as “Click-to-Run” or the Windows 10 Microsoft Store app.
This only applies to the software and not to the storage of any data so nothing is synched back to the cloud just by having an Office 365 for Home subscription.
You can however combine it with a mail account which does sync with the cloud such as IMAP (mail only), Outlook.com (mail, calendar, contacts and tasks) or an Exchange account (full mailbox)
Note: POP3 accounts don't sync anything (not even read/unread status), but you can configure it so that you can at least receive your emails on all your devices. Alternatively, you can use your current POP3 address to sign up with Outlook.com and be able to sync your mail, calendar, contacts and tasks between devices.
Office 365 for Business
Office 365 for Business is almost the reverse of Office 365 for Home and does actually store your data in the cloud (amongst other things). For Outlook, the component of Office 365 for Business which does this is called Exchange Online.
As said before, an Exchange account will sync all your mailbox data via the cloud with other computers on which you have Outlook installed. This data can also be accessed and synched via practically any tablet and smartphone or via a web browser.
The most complete subscription of Office 365 for Business also includes a license for the latest version of Office Professional Plus. This is offered in a similar way as with the Office 365 for Home subscription.
Signed in with Microsoft Account doesn’t sync Outlook
When you are signed into Office with your Microsoft Account, then various Office settings are stored “in the Cloud” which are synched to other devices on which you use an Office 365 installation (or any Office 2013, 2016 or 2019 suite).
It also allows you to connect Office with other Cloud based services such as OneDrive, Facebook, Twitter, YouTube, LinkedIn, Flickr and some more.
In any case, signing in with your Microsoft Account to Office 365 for Home, Office 2013, 2016 or 2019 doesn’t mean you are synching data stored in Outlook with or via “the Cloud”.
As mentioned before; You need to use the correct type of mail account if you want to be able to sync your email, calendar, contacts, tasks, etc… stored in Outlook.
Sharing via Office 365
When you want to share your data with others, then the other person must also be on Office 365 for Business. In addition, this person must also be part of the same Exchange Organization (read: a license within the same subscription account or ‘tenant’). Both having an Exchange Online subscription of your own will not be enough and won’t allow you to share folders.
An alternative would be to create a new IMAP or Outlook.com account and then share credentials.