Pls download Facebook because i need Facebook

If your details are correct and you have an iPhone 5c, then you cannot update beyond iOS 10.. simply because that phone is too old. Nearly a decade since it was released.

Facebook app requires at least iOS 12. So if you need Facebook, then you'll need a newer model iPhone

If you're asking the same question as the original poster, then the answer has been provided.

If you are asking something else, start a new thread or explain more clearly what your issue is

Writing an effective Apple Support Commun… - Apple Community

I want lite Facebook but i can’t