Hello Mayerlyn,
Welcome to Apple Support Communities.
I have read your post and you are wondering which workout mode to set when working out using a Maxi Climber XL, correct? I'm here to help you take a look in to that!
After looking into the Maxi Climber XL, that is a really great question. It appears it could be a Stair stepper, but there is also the Other option in the Workout types. Here is an article that outlines the various workout types:
Workout types on Apple Watch
I would encourage you to reach out to Maxi Climber XL for any recommendations as well.
Happy climbing!
Take Care!