If you go to very leftist areas of the internet (socialist or communist areas, anywhere from anarchistic (bottom left) to authoritarian (top left)) you’ll see people using liberalism by its political science definition, rather than the definition its taken on within American culture. It stems from the idea of capital moving freely (that is, liberally) without restrictions. You’ll also see it referred to as neoliberalism in the same spaces.
Full disclosure, I myself am pretty extremely socially libertarian (arguably borderline anarchistic), and have used liberal derogatively myself.
The call to action button is the free plan, with subscribe having a secondary button style. That alone makes it clear they want to show you ads more than they want you to subscribe.