Theme elements via VC composer not working

Hello

I have got Fortuna as the one of the most elegant theme for our business, I purchased it but i am facing a big issue that when i add any new row or element on page//post. the page stops working.

For example, if i a a simple element to page like post carousel to page then publish it and view it in browser, it shows blank page like, only header shows and not section, post even footer not shows.

link below:

https://www.atlanticchoice.com/car-hire/

Kindly resolve my issue ASAP. thanks