The map doesn't seem accessible anymore, a least not via the public link. If the shared public link doesn't work and the map still exists then its only visible to the original creator and people the creator has specifically shared it with. That would via My Maps in your Google account, unfortunately I haven't found a reliable method of searching for a specific publicly shared map 😞
I think given the age of the first post the map was created with old Google Maps, that changed to My Maps around 2019, old maps were automatically upgraded, but I suspect the link will have changed.