Devs were kind enough to explain it to me so I guess this version will never have online it's sad but oh well :(
This is what they said on discord to me:
"About the multiplayer, I have asked for confirmation and it wasn't removed due to a lack of sales. The Solar Challenge Edition is essentially the base game + all DLCs in a discounted bundle, but without the multiplayer component. This applies regardless of the platform this particular edition of Redout is sold on (multiplayer is absent also on the Epic Games Store if you buy the Solar Challenge Edition, for instance)."
Post edited March 28, 2022 by NetSphereEngineer