The standard alarm starts 20 minutes before your wakeup time to increase the light. The sound will start at wakeup time with zero volume so you should hear it about 2 minutes after wakeup time (which is 22 minutes after light start).
For testing purposes we recommend to disable all rising times and forerun times sound in the alarm settings so you can hear the effects immediately.
You can test if the sound works in general by going into the sound settings of your alarm and tapping on “Final sound volume”. You should hear a preview of the sound on full volume. Also check in the settings that “Control system volume” is enabled otherwise the sound will not be hearable if you put the system volume to zero.
The alarm might be suppressed by your do not disturb mode. If you are using a „do not disturb“ mode in the time where the alarm should fire be sure to set it either to “Alarms only” or add an exception for the app in Android settings.