You're reading the public-facing archive of the Category Theory Zulip server.
To join the server you need an invite. Anybody can get an invite by contacting Matteo Capucci at name dot surname at gmail dot com.
For all things related to this archive refer to the same person.
Just a quick heads up in case any of you aren’t on the categories mailing list. The London Mathematical Society will be running a 7 week online category theory course: https://www.icms.org.uk/V_CatTheory.php