How to download apps on an Apple Watch without a passcode?

I am trying to download TikTok on my Apple Watch, but it is requesting me to enter a passcode, but I do not know how to find out what my passcode is or if I even have one, and I’ve tried entering codes that I use for other things on my Apple phone But they do not work. How can I go about finding my passcode?

[Re-Titled by Moderator]