The username you used to log in to the forums, Nebula_Storm, only has replays from 2013-2014, long before Steam linking was required (the requirement started in 2019)
If you played FAF in the last 7 years, that means you have two FAF accounts. Log in with the other one.
Or, if you haven't played in the last 7 years, then you never did Steam linking. So go ahead and steam-link your account:
https://forum.faforever.com/topic/3800/what-is-steam-link-gog-link-why-is-it-required-and-how-do-i-do-it