First time, problems with interface Behringer or Focusrite when is youtube in the ground. Help!

Hi, with the focusrite one or behringer , i have in this setup:

Wasapi selected for server.

Interface (Focusrite or Behringer) for Record.

And in origin of record (Same Focusrite or Behringer)

In one of them i see put loop in ( ).

Whats the problem, when is youtube in the ground and you wanna record, is giving me error msg about the sound card is not ready, the program captures the use of the audio interface only for his use of the app? or is possible add sound by a mic and capture a music of youtube (base of the song) for play with the instrument?

Thanks.

There is something about Audacity recording a stream that requires the stream to be playing first (not paused) to get the audio. It is not something I have ever done, so perhaps someone else can provide details.