I just googled Optum and found this website, United Health Group and Optum.
Optum Products & Services - UnitedHealth Group
My contact with Optum was because I go to MVP Health Club at Brownwood. I use to pay for membership but it became free as part of my United Health Medicare Advantage plan at the start of 2018. When United started offering this benefit two years ago, we were told at the United Health table inside MVP lobby to go to the Optum Group page and get a number, give that number to the front desk at MVP and your membership would then be free. I was told last year at MVP that it is now called Renew and not Optum, and I started receiving a Renew magazine in the mail.
UHC Renew Active