Child domain forward another folder

Hi every one. I install bigbluebutton and cyberpanel same server. i have domain like i create child domain like but i must forward subdomain to /var/www/bigbluebutton-default. But cyberpanel create subfolder in How can i forward childomain to /var/www/bigbluebutton-default folder.

This topic can help you
Reverse Proxy Traffic to Docker Container on CyberPanel

But can you explain how you installed bigbluebutton