Chaotic-aur key

I’d like to use chaotic-aur on my Manjaro system (don’t have the time right now to convert to garuda, sigh) and I’m getting stuck on the very first step:

root@soumak /h/tve# pacman-key --recv-key 3056513887B78AEB --keyserver keyserver.ubuntu.com
gpg: keyserver receive failed: Server indicated a failure
==> ERROR: Remote key not fetched correctly from keyserver.

What am I doing wrong?