Money owed to Federal

[Deseidlitz]

My son owes money on the federal.

It was accepted back in March and he’s been trying to pay on it, but it still says the balance of zero on the IRS website.

Is this normal, what does he need to do? 
He already paid a few $100, when the balance said $0

[DoninGA]

His IRS tax account should have the information required - https://www.irs.gov/payments/online-account-for-individuals