Those are weird units indeed :
(1 km /s) / 1 mega parsec =
(1000 m/s)/(10^6^ x 3.0857×10^16^ m) =
1/3.0857×10^19^ seconds =
1/978 x10^9^ years.
So, when we multiply by the rates (which are either 67 or 74) we get :
1/ 14.6 giga years or
1/ 13.2 giga years
… basically ( 1/ “age of the universe”).
Meaning physical observation disagree about the age of the universe …or the theory is faulty.