I have not personally had a Deloitte Digital Case, but couple of pointers in general for final round. For experienced hires top consulting firms want to see that you understand the industry with a bit more depth than students. In my experience - if you are able to make the interview a discussion, conversation - you will be successful. At this stage the basic HR questions are limited and it is more about giving you a case to work through but apart from basics look into:
1) Why are companies going Digital?
2) Do you have a few specific examples of new Technology being used?
3) Think about banking vs retail vs consulting industries - how and why is each one changing towards digital?
I prepare my experienced hires to run these cases as convesration - where you bounce ideas and discuss industry. Deloitte will want to know that they can put you on a project tomorrow and you will be credible with your client.