Hi HF Netherlands,
Could you provide us with the detailed information about "we receive constant synchronization conflicts in the folder Problems with synchronization"? If you get any error message, please post it.
In order to troubleshoot the issue, please try the steps below:
1. Rebuild a new identity database, and then connect the Office 365 account in this new identity.
2. Please connect Outlook 2011 to the Office 365 account on another Mac. Will the issue occur?
For more detailed information about "Rebuild the Outlook for Mac 2011 database to resolve problems", please refer to the following article:
http://support.microsoft.com/kb/2360509
For more detailed information about "Set Up Outlook for Mac 2011 for Your E-Mail Account", please refer to the link below:
http://help.outlook.com/en-us/140/gg471164.aspx
Thanks,
Edward Qu