After clicking the above link, do the following:
Click Connect Audio.
If asked to allow microphone access, allow it.
(You will be muted, but the software requires microphone access.)
You may need to plug in headphones or a cable in your microphone port.
Or you can enable a recording device:
If you get a busy signal, try the following:
(Listening online instead of by phone may free up phone lines for others.)
Place your call early.
Hang up and redial until you get through.
(This may take a few minutes.)