@ccorry21 , no, you do not. Personally, when it comes to the car buying experience, I would always plan to come already pre-approved from your financial institution. Though it depends on your own financial situation, generally, rates from your financial institution or CU are better. There are some caveats - if 'brand' (Kia in this instance) financing is 0% APR for X amount of months or there is a $$ incentive, it may be in your benefit to go that route. You could also take the incentive and refinance that loan later down the road. The current incentive is $500, which for our personal taste, isn't worth it to take and then refinance.
But, no, you do not have to finance through Kia (or their third party).