=iferror(indirect("Sheet1!A" & min(arrayformula(if(Sheet1!A$2:J = A2, row(Sheet1!A$2:J), )))), "no match")

=ARRAYFORMULA( IF(ISBLANK(H2:H),,VLOOKUP(H2:H,Sheet2!A2:C,3,FALSE)))

=ARRAYFORMULA(IF(ROW(A1:A) = 1, {"USERNAME", "PASSWORD"}, IF(ISBLANK(H1:H),, {VLOOKUP(H1:H, Sheet2!A2:C, 3), FALSE), VLOOKUP(H1:H, Sheet2!A2:D, 4, FALSE)})))