In Outlook 2016/365 ActiveSync support is not enabled by default. While it is still possible to use the manual setup procedure through the Windows Control Panel, unfortunately auto-discovery does not work in this case.
Alternatively it is possible to enable ActiveSync support in Outlook by creating a registry key as follows (source):
- Close all Office applications.
- Start Registry Editor (regedit.exe).
- Locate and then select the following key:
- On the Edit menu, point to New, and then click DWORD Value.
- Type EnableEASAccountCreation, and then press Enter.
- In the Details pane, right-click EnableEASAccountCreation, and then click Modify.
- In the Value data box, type 1 to enable, or 0 to disable EAS account creation, and then click OK.
- Exit Registry Editor.
You can now create ActiveSync accounts using the regular account creation wizard in Outlook by selecting Exchange ActiveSync as account type.