Help me understand the 15 hours free childcare.

My child attends nursery 1 day a week.
The nursery initially didn't apply the free childcare but have now revised the invoice and issued a credit note.
The day is 8am to 6pm
They are applying 5.6 funded hours to the day my child attends

I believe at 15 hours a week, 38 weeks per year, we should be getting 570 hours per year.
Based on the 5.6 they are applying though, that would amount to only 212.8 hours per year.

I need to speak to the nursery obviously but I need to try and understand this better before I do. Am I missing something here about how it works?

Even if the hours are spread over 52 weeks, the free hours are still short I believe.