You can start this quest after getting the Eos vault up and running on Eos during the quest “A Better Beginning”. While the first phase of the quest was contained to the Nexus, the next ingredient is right here on Havarl. During the quest “Helping Havarl’s Scientists” you’ll have to travel to a monolith southeast of the Pelaav Research Station (the southern-most monolith on Havarl, in fact).

As soon as you enter a Remnant structure north of where the Remnant Console can be found (where the Angaran scientists are stuck in stasis) head down a ramp and turn east, where you’ll find some fungus that can be “distilled into a drink”. It’s along the edge of a rocky shelf, under a larger, much more prominent bioluminescent mushroom. Scan it, then return to the Vortex on the Nexus and give the alien fungus to Anan T’Mari, which will net you 150 XP.