Unable to install theme

Permalink
Hi I have purchased a theme, associated it to my project, but when I go to add functionality the theme is not there. I am using the latest version of C5, all my other sites are still on 5.7.3 or below, so im not to familiar with this framework

 

This website stores cookies on your computer. These cookies are used to improve your website experience and provide more personalized services to you, both on this website and through other media. To find out more about the cookies we use, see our Privacy Policy.