Mega Menu Plugin does not work on mobile

Hi, I have just started using a plugin “Mega Menu”.

As you can see, it is fine on https://ibb.co/GQwBBJx desktop. However when it comes to https://ibb.co/gzr897C mobile, all the sub menus are gone as I am not able to see them even I click the + to open the sub menus. I think the mega menu mobile is not overriding the default theme menu?
The name of the theme is Charitas Lite.

Thank you for reading.

• This topic was modified 2 years ago by Jun.
• This topic was modified 2 years ago by Jan Dembowski. Reason: Moved to Fixing WordPress, this is not an Everything else WordPress topic
• This topic was modified 2 years ago by James Huff.

The page I need help with: [log in to see the link]