This is a Chrome issue not an Optymyse issue.
You may need to ensure you allow Optymyse in the site settings in Chrome. Otherwise Chrome will block playing sounds.
Go into your Chrome settings, Click advanced, click site settings, scroll down to sounds.
Check site settings and ensure your Optymyse URL is in there in the allowed list and make sure sounds are enabled.
Depending on the Chrome version another fix is to enable autoplay mode in Chrome.
To do this follow this link chrome://flags/#autoplay-policy
On the Autoplay policy dropdown select "no user gesture is required"
Click the relaunch button and your browser should restart