Did you completely conquer the Fallen Empire? You get the databank if your war goal is, "Technology Acquisition," so if there is only one Fallen Empire and you eliminated them, you may not have the option to get the databank via brute force.

If there's a dropdown section in the, "Mystery of the Precursors," situation it should tell you your options to get the databank. You can get the databank from Phanon, the Curators and the, "Technology Acquisition," war goal against Fallen Empires. You need to pay both Phanon and the Curators a hefty sum of money. I think those are the three options.

If there isn't a dropdown section in the aforementioned situation, I don't know what you could do. You could still try talking to Phanon or the Curators, but that's speculation.

I usually go for the Curators, it costs 100k Energy Credits, and 10k of both Dark Matter and Energy. The option to buy the Databank from the Curators is under, "Tell us about the Precurors," section in, "Tell us about the past." You need excellent relations with them, I'm thinking +70 relations? But I'm not sure.

I hope this helps.

Thank you so much!!!!!!!!!!!!!!!!!!!!!!