I’m completely new to Miro. I installed the Miro plugin in my Confluence server.
When I tried to add the Miro macro, a window pops up with the option “New board”. I clicked it and it hanged with a loading circle. I tried waiting for half an hour, no change.

No error other than the initial 403 when I opened the popup:

Network traffic stopped at splitChanges:

I’ve allowed “miro.com” in Chrome third-party cookies.
Tried Incognito too, same result:

What else do I need to do to get Miro working in Confluence?
EDIT:
I went to miro.new to create a board there, afterwards I can embed that into Confluence.