HI:
I say that your diagram documents neither functional requirements nor business requires, but a system implementation. Functional requirements diagrams show functions and - especially - the function's data inputs and data outputs. Your diagram does not have data input or data outputs. That is what is so confusing about BPMN - it says that it is about business processes (i.e. business functions) but it is not.
Only data flow diagram capture data flows (data inputs and outputs between functions).
As far as business requirements, see the below which I copied from Wikipedia after querying on "business requirements".
Tony
Business Requirements
Example: Improve the readability of project plans.
Funtional Requirements
An example that follows from previous business requirement example:
(1) System must provide the ability to associate notes to a project plan. (2) System must allow the user to enter free text to the project plan notes, up to 255 characters in length.