How do you find your knowledge base?

Were you looking to access Siyuan in your browser? What do you mean by "find your own knowledge base?"

Just tell me how to access it after paying. Please

What do you mean by "knowledge base"? The documentation is accessed through the "User Guide" option, which appears as its own notebook.

I don't think that just because it doesn't match your expectations doesn't mean it's a scam.

If you look at their github commit logs (dev), you'll see that they update Siyuan almost every day.

Anyway, have a nice day!