The 1830 typesetter accidentally omitted the determiner their before wages, but it was restored in the 1837 edition, apparently by reference to 𝓟. As discussed earlier under Alma 11:1, the text normally has either his or their as the determiner for wages. The critical text will, of course, maintain the their here in Alma 11:20.
Summary: Maintain the determiner their for wages in Alma 11:20 (“because they received their wages according to their employ”).