Welcome :)
I am not sure what the issue is exactly but I'd try to guess. Correct me if I am wrong please.
Is the problem that icons do not appear, but instead just some text?
If it is so, then that's because you need to set the attribute "icons" to "font".
Here are the details
http://asciidoctor.org/docs/user-manual/#admonition-icons. But the summary is that you need to add the line ":icons: font" under your document title.
Optionally you can pass it as an attribute, but how to do that depends on your rendering tool: ruby, java (asciidoctorj, maven, gradle,...), atom,... other?