HBO MAX sign in works on one computer but not the others

When I sign into HBO Max through my Xfinity subscription on my work laptop (2015 macbook air), HBO max shows me my account and I have full access to the site. However, when I try to sign in through my Xfinity subscription on my personal laptops (2013 macbook and 2020 macbook air), I get the message that I am a secondary user and need a primary user to create a login. Why would I get that message on some computers but not all? Is there something wrong with my personal computers' caches or browsers that is causing this, and how can I get HBOMAX to work on all of them? Why would I need to create a new account with the "primary user" if HBO Max works for my normal log in on my other laptop?