The key thing to understand is saving saul happens during that riders on the storm mission, where you'll need to work with panam to infiltrate this cement factory the raffens are using as a base. Before going in, mitch helps you scout the place with his drone which is super helpful for planning your approach, and you've actually got some decent options here.

If you're good at stealth and have decent tech skills theres this ventilation system you can use to sneak in, or you can try working your way around the outside if that's more your style. Combat works too but honestly, stealth makes things way easier especially when you're trying to get to the basement where they're keeping saul. Once you find him though, that's when things get really interesting because you've got this whole escape sequence through a sandstorm which is pretty intense.

Tip: keeping saul alive is actually pretty important for the story especially if you're thinking about romance options with panam later on. Also might be worth mentioning you get this really nice sniper rifle called overwatch as a reward, and it's definitely worth holding onto.