The first one is grammatically wrong, the second one is a wrong translation.

The numeral removes the requirement for an article so that should be:

J’ai cinq voitures rouges.

Variants would have a different meaning:

J’ai les cinq voitures rouges.

I have the five red cars (There are exactly five red cars and they are all mine).

J’ai cinq des voitures rouges.

I have five out of the red cars (There are more that five red cars, five of them are mine).