As I understand, you're getting past the first fight but having trouble on the second. You said your gear is in the 30s but if it's normal quality ("white") gear it can still be low. I recommend picking up a high quality vintage picatrix for your weapon at least.
You can Google a couple of videos of people doing the fight 4 years ago. The basics should be the same. The healer can hold off against the summon so you can focus on the summoner. This lets you use Ifrit or Emerald for more damage. Stand far away from the healer so they don't get hit with the AOEs, keep Bio and Miasma up, use Energy Drain for some extra damage, heal yourself as needed.