How are you determining that your user profiles are communication with each other?
Your screenshot shows that you're looking at the "install available apps" feature which would allow you to install TikTok in a separate user profile, provided that it is installed in the Owner profile or it won't show on that list.
Is there some other way you're determining some unexpected behavior? If so, I'd be happy to look at that, but I'm fairly certain that this is a case of not quite understanding how things work quite yet, but with some additional context about what you think is happening, I'm sure I can elaborate on this :)