The sentence doesn't have any problems with grammar, but as Irene already said I'm not 100% sure what you mean by 'memorial meeting'. I think you might mean 'memorial service'. Did a group of officials have a meeting in the square where they discussed a memorial service which will happen in the future, or did officials and members of the public meet at the square to show their respect for people who have already passed away? This gathering to show respect is usually called a memorial service, see this example news article: https://www.theguardian.com/australia-news/live/2019/jun/14/bob-hawke-memorial-labor-sydney-politics-live Hope that helps!

Mostly. What does “memorial meeting” refer to?

Yes!