You should always hire a certified professional water damage cleanup company. If you hire someone that is not certified your insurance company may not cover the insurance claim. A certified professional will have the necessary equipment to properly check for any and all moisture. Additionally, they will have the proper equipment to remove it too.
If all the water is not removed it will cause mold growth. Mold growth will lead to a larger cleanup cost. Our insurance company wants to minimize the amount of damage to your property so they will be able to reduce the amount paid out. That is why your insurance company is so adamant about you working with a certified professional restoration company.