First, please make sure that you are connected to a reliable WIFI network. Pop-up blockers on your specific computer may prevent Zoom from downloading, so be sure those are turned off. For further help connecting or getting started, please visit the Zoom Support page for further help.
If you’re not hearing any audio, double check to make sure you device isn’t connected to another device or bluetooth speaker. In Zoom, go to Preferences > Audio and use the “Test Speaker/Microphone” prompts to troubleshoot. If you still need help please visit the Zoom Audio Support page for further troubleshooting.