I currently have MVP healthcare as the insurance provider. You can use whoever you want that is available in your part of the country. Just make sure it is a HSA compatible plan (HDHP). I always make sure my plan is HSA compatible even if the premium is slightly more. I more than make up for it in tax benefits plus compounding within the HSA.
I was looking at MVP Healthcare & their documentation says they have their own HSA with a bank. They let you use Fidelity even though they show their HSA accounts hooked to a bank they work with?