How To Get The Atlantid Drive

I've returned to the game after a very long absence, so I am unsure about my progression.

I need to get the Atlantid drive so I can travel to a purple system for ingredients to craft some upgrades. I'm trying to figure out if I have finished the required mission "In Stellar Multitude". All I know is that I have a star seed installed, warping and pulsing don't trigger a mission. I can speak with Autophages, and have purchased upgrades and crafted staves already, if that's any indication. I can travel to dissonant systems, which some suggest can trigger being given the blueprints for the Atlantid drive. All of this, but I still don't have the blueprints or any idea how to proceed or tell exactly where I am in the process. I'm not even sure how to identify a purple system on the warp map as none of the systems look purple (mostly pinkish at best). I'm sure I should be able to see them even if I don't have the drive I need to ravel there.

Any ideas on how to proceed?