Outstanding debt Resident Return

Hi, i recently was granted a resident return visa in june 2023. This august 2023 my friend received a ltter with name to pay outstanding debt. This is the bill for quarantine that i did in 2020 I immediately paid all.the amount and called revenue nsw, it seemed they had my incorrect email address and i received no previous notification from them.
My question is, when i appied for RRV the last question is if i have any oustanding debt. I answered no because i wasnt aware. What ahould i do now?
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