No Dropdown Menu Appearing

Hi,

This plugin sounds ideal for my site, as I’ve only recently guessed that my custom theme doesn’t support mobile menu options, or so it would appear. I’m a semi-beginner with WordPress, but I think my issue here is that I’m not using the correct Menu Container Class / ID for my site.

I’ve tried:
#navbar
#nav
#custom-menu
#current-menu-item
#wp-nav-menu

My site is https://www.magneticnorthfestival.ca

Any suggestions would be greatly appreciated. Thanks!

https://www.ads-software.com/plugins/jquery-responsive-select-menu/