Interface button stopped working

Hi, all.

Both the ‘Apply’ & ‘Apply now’ button on my ‘Work with us’ Page seems to have stopped working.

Originally it would open up a pop up box – which would contain inputs for an applicants name, phone, email, extra information, and an option to attach a CV.

I might be being slightly dense, but cant for the life of me figure out whats happened with it.

The code for the ‘apply’ button is below

<a class="btn btn-tertiary" href="#" rel="noopener" data-toggle="modal" data-target="#apply-modal">Apply</a>

Any help or input would be greatly appreciated.

Thanks

Rob

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