Now some WebOffice files have to be deployed to ArcGIS Server.
Copy the folder WebOfficeSystem from WebOffice10.9-DVD\Software\WebOffice directories\ to <ArcGIS Server location>\directories (usually C:\arcgisserver\directories). The folder WebOfficeSystem should contain one folder and the file syn_soe_ao_gateway.json.
Content of the subfolder of the synergis directory
The file syn_soe_ao_gateway.json contains the relative paths to the files mentioned above.
Adjust file paths if different from standard paths