Walmart OnePay is issued by synchrony bank and you can access it if you have many retail cards issued by synchrony. I can access it using my jcpenney card or my lowes consumer card. However, synchrony seems to be requiring a new login where they lump these together with a login directly to synchrony. It appears this is the one that quicken has to get set up. It is not a choice in the currect selections when you try to set up the account in Quicken. The URL that has to be setup in quicken is:
"https://id.synchrony.com/idp/en"
When you login with this method, one your credentials are accepted, the address bar changes to:
"https://www.synchrony.com/accounts/"
But you can't login using that address directly. Any retail card that gets you to synchrony account manager will give you access to your synchrony retail cards.
To get to account manager directly which is the "new" login that synchrony has directed people to. This is the one that Quicken seems to have to get setup in quicken because there is no option to get to this with any current Quicken selection when you try to set up your account.