My store is up and running and I am the facebook business manager. I created a Pixel that works perfectly.
The only this is when I want to create a catalog on facebook using the pixel, it is impossible as facebook tells me that the pixel is not ready (even though it is working and it has already fired a lot...)
There are 3 options to adding products to Facebook catalog,
you're trying to add products with the third option which is a bit complicated to use, it's a bit confusing as it says "Connect Facebook Pixel",
I recommend using the "Add Manually" or "Use Data Feed" options to upload your products,
the event data source connects your pixel to your catalog, as long as you marked it there it connects all the events (add to cart, purchase..) to your catalog, it will all work the same with the first two options to upload products.
All the best!
Gabriela, try doing so through Business Manager. If you don't have such an account yet, set that up. It is best practice to have one as you are easily able to manage all your Facebook assets and users. In Business Manager, you can assign your pixel to the ad account and catalog.