I’ve tried everything possible and I still cannot get audacity to pickup the sound waves from Behringer. The behringer model is UMC404HD. I am using a Macbook PRO. The audacity version is 2.3.2.
If you’ve tried everything, I guess there’s nothing else to try… 
Is the Behringer selected as your recording device in Audacity?
What’s plugged-in, a microphone? What kind of microphone? Etc.? Which input(s) are you plugged into?
Are you getting any “blinking lights” on the interface indicating a signal? Can you hear anything with headphones plugged into the Behringer? (It has “zero-latency hardware-monitoring” so if you’re getting sound into it, you should be able to hear it without the computer or software.)
Check first that the Mac sound system recognises the device. Once that is working, launch Audacity and select the device in the device toolbar.