Office 365 on Meraki is tricky. As far as contact import goes, I think the easiest solution is to prepare them via CSV file for import. Meraki has strict guidlines for the formatting of the CSV file.
The CSV file should be formatted as follows:
One row of headers at the top of the file
One column named "name"
This will create as many new contacts in your directory as there are valid name rows
Optionally, columns named "number" and "type" which describes the type of other number that you want to assign to this contact
The number must be a valid phone number with no additional special characters
The following types are valid: Apartment, Home, Mobile, Office
If no type is specified, the numbers will be added as Office numbers
Any other columns in the CSV file will be ignored
I'll attach an example to this post of what it would look like.
Moving forward with MDM and ActiveSync just create a profile and put it on a tag. For ActiveSync settings on the profile put outlook.office365.com as the Exchange Host, check Use SSL, and for User set Use Device Owner. The for each iOS device set an owner, using their email address as both the email and the username, and add their tag. All the users need to do is set a passcode and enter their password for 365. To keep others out then you will need to enable device quarantine on Office 365. Just as a warning, when you do that it is going to quarantine all devices that are currently connected and you will need to go through and allow them (assuming you want those connecting anyway).