Tik Tok didn't notice you. Can I text him?

On Tik Tok, you can send messages to each other without paying attention to each other. If you pay attention to him and he doesn't pay attention to you, you can only send him three messages.

So, after he replies to you, you can continue chatting or wait for him to pay attention to you. If you two care about each other, you can become friends and start chatting.