In order to link ArcMap and ArcGIS Pro with the WebOffice 10.7 SP1 author standalone, you must click on "Install ArcMap Connector Extension" and "Install ArcGIS Pro Connector Add-In" during the installation of the author standalone to install the corresponding connector add-ins.
ArcMap Extension
Open ArcMap and choose Customize -> Extensions. Tick WebOffice author standalone. The ArcMap extension is now connected with WebOffice 10.7 SP1 author standalone.

ArcMap Extensions
Now the WebOffice author standalone can be selected via Customize -> Extensions -> Toolbars and the toolbar can be integrated.