There are 2 ways.
1. For notification of new posts in a specific Forum Topic, just "follow" that category. Click on the three dots on the right and select follow category.
2. To get email notification of posts by member (covers all categories) go to the member tab and the list of members. Select follow on any (or all) member. The follow box goes to white on those you elect to follow.
It's just that easy to get all the latest posts.