Once a Real Estate Agent has been invited and logged in to the Agent Portal, they will see a list of all active loans they have been granted access to (including any loans created by applying through the Real Estate Agent's Co-Branded POS URL). In the dropdown in the upper right corner, they can switch between different brokerages if multiple brokers have invited them to loans.
Click on a loan to expand it's details, progress in the loan process, pending/in review/accepted Client Needs, or even upload documents, such as the purchase contract. Documents uploaded here will appear to the Loan Officer in the Documents tab of the loan.
If you chose "Pipeline & Pre-Approval" as the Agent's access level in the Pre-Approval Access pane under the Setup & Contacts tab of the loan, they can click on Pre-Approval to edit and send the Pre-Approval Letter, restricted by the limitations you set in the Pre-Approval Access pane for the loan in question.