How do you get Nomorobo installed on phone

I can't get it to verify either. We received a letter from Cox saying our line was ready to set up Nomorobo. I followed the steps exactly, enabled Simultaneous Ring and entered the Nomorobo phone number in Phonetools as indicated. But when I get to the Verify Protection screen on the Nomorobo site, I get a call but the recording says it's either not set up correctly or unable to verify. One instruction says to pick after the third ring, another says to wait until the color bar changes color. Tried both and the same issue.  I checked everything with Cox support and they have no idea why either. Nomorobo is no help, I sent an email but who knows when they will answer as the response is that it can take some time.