How do I add my business email to the Facebook account?

I have been having trouble trying to add our business email to our Facebook account. It was set up under the owners name, using a phone number. I tried to replace the phone number with an email and have also tried adding the email in addition to the phone number. Nothing will work. It keeps popping up an error message. This is frustrating because I need information to go to the business email, such as invoices for our ads. We have too many vendors to remember to log into to individual accounts and see invoices. I have tried talking to the Facebook team and they don’t even understand the question. Or they lead me right back to where I keep ending up, at the error message.