Apologies for the delay. There will not be a compatible version of the current extension for GM:Studio 2 (because porting to GM:Studio 2 would basically mean rewriting it).
In the coming months I'll be making a decision regarding the "rewrite" -- the eventual replacement for GameMaker Server built for GM8 up to GM:Studio 2. Please keep in mind it won't necessarily be a "positive" decision. If I continue, I want support it for the next 10+ years, like I have done with GameMaker Server.
In short: there's nothing I can say for now, but check back in a few months.