Howdy and welcome to the forum!
The pets, however obtained, are restricted to subscribers only. If I remember right, you can also earn the raven and the blue fox by completing certain free levels.
I’ve a test character, dedtest, who is ftp and is at about lvl 36.5. He’s also completed all of the free levels in the main campaigns…however, I’ve not taken him thru the HOC, or other, campaigns yet. It might be possible, especially if you can get as far as you possibly can in the repeatables. Here’s a link to the topic with the HOC content: