Due to an influx of spam, we have had to temporarily disable account registrations. Please write an email to accountsupport@archlinux.org, with your desired username, if you want to get access. Sorry for the inconvenience.
https://lists.archlinux.org/archives/list/arch-dev-public@lists.archlinux.org/thread/5GU7ZUFI25T2IRXIQ62YYERQKIPE3U6E/