“Beggars can’t be choosers.”

What does it mean?

If you’re asking for a favor from someone else, you have to take whatever they give you.

Where does it come from?

‘Beggars should not be choosers’ didn’t appear until John Heywood’s 1562 version of ‘Proverbs’.

Beggers should be no choosers, but yet they will:
Who can bryng a begger from choyse to begge still?