El administrador no puede cambiar el nombre de usuario

[simon]

@hmbdiscoursehelp

If I “uncheck” the “sso overrides username”, will people be able to create their own user names? Is there any downside to that?

Yes, unchecking that setting will allow users to change their usernames on your Discourse site. The only downside I can see is that if a username is edited on Discourse, but not on your SSO provider site, the username won’t match between the two systems. This won’t cause any technical problems, but depending on how you are using Discourse, it could cause some confusion among your users.