5万齐了
totally 50000 confirmed

When someone says 齐了, he confirms the expected total amount or number is satisfied.

Example:
客人都到齐了。
All the guests (that we expected) have arrived.

It mean all of the 5 万，

in its entirety

all, wholly

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Note added at 4 mins (2023-09-23 04:45:08 GMT)
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in full

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Note added at 3 hrs (2023-09-23 08:00:16 GMT)
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It simply means “the whole amount of 5 万”

5 万 has been paid in full;
5 万 has been received in full;

You don't owe us anything any more.

Or I don't owe you anything anymore

depending on who is saying it.

As you said it's conversation, it should be someone collected 50,000 and said the amount is 50,000 now.

So we should make the translation also conversational.

The sentence translates to "Is the 50,000 ready?" or "Have you gathered the 50,000?"

It's common to use 齐了 for such phrasing when dealing with gathering/pooling money for something.