Hey! I figured it out. I had mistake in my syntax. There must be a forward slash before “c” in the link address. Like this:

[cats](/c/cats@sh.itjust.works)
       ^

cats

I was omitting that forward slash, because you could do that on reddit. I hope they fix that to work here as well. Actually simply writing the link like this c/cats@sh.itjust.works in regular text should create a link.