If you are just starting with that account, don't test with conversion campaigns. It's too costly and you won't be able to gather enough data to make them profitable from the jump. Use lead generation campaigns where the form is within fb to populate your pixel with 100% accurate data. When you use the pixel right now depending on where you are targeting (If its a tier 1 country where most people in your demographic are using iPhones) you might see less than 30-40% match score.
You have to manually optimize that way you can give the AI a fighting chance. With these new pixel blocking / privacy updates, Fb has reduced its effectiveness yet the CPM's are still growing. I've been doing fb ads for almost 8 years now and it's a different ball game.
Pass UTM parameters to Google analytics to track 3rd party and use proper naming conventions. With that you can use the data from GA to manually optimize your fb campaigns and once you have it drilled down manually you can let the AI try to work with the drilled audience.
Trust me when I say, you don't want to let the AI try and find who's who right now. Unless your product is super viral and general with a high AOV or LTV; you'll bleed money if you aren't manually optimizing.
Also use CAPI and make sure you set the priority of what event is most important for you. When you use Conv campaigns it's really important to have this done.