I can't understand why, on online tours, when my tour starts I don't hear the audio. How can I solve this?

On the loading screen the videos or audios do not sound until clicked because it is a limitation of the browsers.

To avoid this, we recommend indicating that you have to click to start the audio.
Or put the video / audio instead of the loading screen, as the first media (in this way, the warning screen of "Enable audio: Yes / No will appear)

You can learn more about it here: https://www.3dvista.com/en/blog/enable-video-and-audio-how-to-get-rid-of-this-window/