This can be stated in active form. Alternate translation: "then the family of the dead man must not let the widow marry someone" (See: [[rc://en/ta/man/jit/figs-activepassive]])
This is a polite way of talking about having sexual relations. Alternate translation: "shall have sexual relations with her" or "shall lie with her" (See: [[rc://en/ta/man/jit/figs-euphemism]])