Logging in puts the + sign in the top-right corner of every page, which I think is pretty self-explanatory and much like the workflow in jira.

Some users have an extremely strong assumption that they need to login before they can take actions; this assumption is so strong that they'll, e.g., miss a large link or button labeled "Create Task" when their goal is to create a task. (If this is the case, it is likely we would want to make much more substantial changes than adding a tip/icon.)