There is an issue with accessing the Atlassian Maven Repository (see Confluence 9.2 release EAP available now - #5 by VasylynaBurger).
You may also want to update the repository URL according to the documentation at https://developer.atlassian.com/server/framework/atlassian-sdk/working-with-maven:
We are in the process of deprecating all maven.atlassian.com URLs. If you are using any of those, please change them to a URL mentioned above as soon as practical. We will advise the developer community more widely when we expect to permanently decommission the maven.atlassian.com URLs.
Currently, AFAIK, non of these URLs are accessible to the public.