Streamlabs OBS for Android and iOS is a free streaming app that is great for testing things out before you make the jump to a paid software.
NOTE: We're aware that this app may be buggy, and sound loss in a live stream is, unfortunately, not uncommon. Use at your own discretion. If you're looking for a more solid option, and are willing to pay for an app, please consider OBS Camera, which you can download from the Apple store. If you are an Android user, consider using CameraFi. If you move forward with Streamlabs, here's how you can try to troubleshoot audio issues on your end.
Since you will be prompted to add your Stream Key and Stream URL in the app, navigate to Content and select Live Events. Choose the Live Event you want to start streaming and click Edit. On the Stream tab, you're going to see a Stream URL and a Stream Key. To make it easier for you, you can copy and paste the Strem URL and Stream Key to your email so you can access that on your phone.
Now Install the app, and once you launch it, you'll see some login options. Select Custom RTMP to connect it with Uscreen.
You'll be prompted to add the RTMP URL and the Stream Key. Paste your Stream URL and your Stream Key here, then click Save.
Next, click Go Live. On the following screen, click on the arrow next to Select a platform and choose Custom RTMP Server. Add a Title and Description (optional) and select Go Live to test your stream.
To test it, go to Content and click Live Events. Select the Live Event you want to stream and click Edit. Then under the Stream tab, click on Test Player. If you see your video/content from Streamlabs OBS, you are ready to go live.
Just note that you sometimes have to wait a good 30 seconds to see your content.