The POI SEO page needs to be live on SpotAngels. ex https://www.spotangels.com/los-angeles/staples-center-parking
Edit the POI URL field of the garage in the Editor. In this case /los-angeles/staples-center-parking
Check to make sure the spot appears as an on-site garage on the poi page
You can link several garages to one POI by repeating the same process
You can link one garage to several POIs by separating the URLs
Ex: https://editor.spotangels.com/#id=413088108 /los-angeles/hollywood-%26-highland-parking,/los-angeles/dolby-theatre-parking