The procedure below is for Enhanced Accounts (AfterLogic WebMail). Enhanced accounts have several advantages, such as sharing via WebMail and ActiveSync (synchronization with smartphones and tablets).
You have to use the Bynari WebDAV Collaborator, which costs US$ 29 and includes a 30 day trial. Details here.
The full installation guide can be viewed here.
After having installed the Web Collaborator, click on the WebDAV Collaborator tab at the top of Outlook.
Then, click Configure > Add … button
Choose your default calendar folder or, if you prefer, create a new one. Note that the server data, contained in WebMail will be synchronized with the Calendar folder you choose from your Outlook, so if you have local data you want to preserve independently, may be better to create a new calendar in your Outlook, to be synchronized with the server.
Set your username (full email) and password.
Keep Web Collaborator open and access Group Office WebMail through your browser.
On the top, click on Calendar > Administration > Double click the desired calendar profile > uplo clique no perfil de calendário desejado > Remote URLs tab
Copy (Control C) the content inside field “Remote URL’s:”
Back to WebDAV Collaborator, paste (Control V) the address obtained in the Server URL field.
Click Detect account settings, which should display a success notice.
Click OK to close the window and in the WebDAV Collaborator, click Synchronize.
Repeat the same process to sync Contacts, accessing, Web Collaborator, Configure > Add … button
The difference is that now you must choose your Contacts folder and as “Server URL“, you need to inform the address specific in Group Office WebMail, in: Address book (on the top) > Administration > Double click desired contacts profile > Remote URL’s tab > Generic URL.. field.