Netflix subscription via iTunes...log in on the Mac?

Have had an iTunes subscription for Netflix for awhile now and watch Netflix via the app on my iPad. I assume that I can watch Netflix on my iPhone and Mac using the same subscription, but when I open the app/site on these other devices, Netflix asks for an account login. However, my iTunes login, the one with the subscription, doesn't work as a login for Netflix. How do I log into Netflix on other devices? How do I associate those other devices with my Netflix subscription? Thanks!