To get the new ARK DLC Extinction running on your server, you will need to do the following:
On our control panel, click steam update to update your server
Then click on custom command lines
Next, you can edit a command line or click on create
Then in the Map box type in Extinction
Make sure the box to the left is selected!!
Save the command line, and to the right make sure to click the select button to activate it.
Reboot the server. Login and enjoy the new DLC!