Hey there!
So gathering souls, you'll need to talk with the person until you overcome something they want. Your initial three targets are Damien, Jolie, and Cassandra. Once you've talked to them three times at the same time slot in the same location, head back to R&D and talk to Mason, who should allow you to make something to help gain their soul gems.
If you need any more help, walkthrough here! https://sinspirational.com/paradise/walkthrough.html