how do i download family shared dlc?

my brother family shared elden ring to me and just got the dlc, according to steam (link below) if i dont own the base game i can still get the dlc through family sharing. "A borrower will have access to the lender's games and DLC, but only if the borrower does not also own the base game" how do i install the dlc?

article:https://help.steampowered.com/en/faqs/view/57A7-503C-991F-E9A8#:\~:text=If%20they%20already%20own%20the,users%20%22own%22%20the%20game.