Permissions for users on a specific report - Server on Prrem

I have recently set up a Power BI server on-prem and am looking to secure a report. This report has data for all departments and I am wanting to have only the user for each department see their own data.

For example - 

In the report, there is data for HR and Finance and there is a dropdown for each. I would like to give permission to the HR user but only to see their data and not that of Finance.

Can anyone tell me the best way to do this?

Thank you