You have to login at https://my.veeam.com
(either with your personal account or, recommended, with the customers account).
On the left hand side you click on "Open a case". Provide all necessary information and collect the logs as stated in the VM KB: https://www.veeam.com/kb1832
If you openend the case please provide us here in the forums your case number, so that our Veeam gurus also can have a look at it.