What to do once you get top 50 in one of the open arenas. Do you get some sort of notification?
Your name will be posted on this list:
lichess.org/@/FIDE/blog/fide-world-fischer-random-championship-lichess-qualifiers/hFQkfMnXKeep in mind that the list is updated every 24 hours, so it may take some time after you get top 50. Hope this helps.