Even reading the comments, this has me confused. "Early Access" is a Steam term, isn't it? Similar to Game Preview on Xbox? I assume he means that the SoD2 file has been made available for those who bought the Ultimate Edition to download so that they can have the file ready for their 4 day early access to playing the game, which is May 18.
Seems pretty straight foward to me.
What is confusing is the 'day 1 game pass' comment. Technically the 18th is day 1 but game pass gets it on 22nd.