On the grantee’s portal page, on the left-hand side you can find the "Navigation Bar."
At the bottom of the Navigation Bar, you can find the section “Requirements”. In order for a Grantee to see Requirements that haven't yet been submitted, the grantee needs to click on the "Requirements Due" tab (see screenshot below). This will display the list of all outstanding requirements for said Grantee. From there, the Grantee would simply need to click on one of the boxes that correspond to the Requirements. That will pull up the requirement and the "Edit" button which, when clicked, allows the Grantee to edit/add information to the Requirement.
To submit a Requirement, see the page How to Submit a Requirement in Fluxx.