Requests
In the Requests tab, business users will be able to see their own requests (Requester, Reviewer) by default.
If the 'Display Team Requests for Business Users' is toggled on for the account, they will also see
Requests submitted by members of their team
Requests where the Business Unit matches their team
Projects
In the Projects tab, business users that are participants of projects will only be able to view linked requests that they have request visibility into (matching the criteria above based on the settings).