Ngrok error Incorrect Usage: flag provided but not defined - How to run it?

Question

I had to get a paid account with ngrok. Before the only command needed was

grok http PORT

Now I had to register a domain on ngrok which is test.ngrok.app.

Now I run: ngrok http --test.ngrok.app:PORT

I get the error: Incorrect Usage: flag provided but not defined:

I don't understand how to run it. Any help would be great! Thank you!!