Hello,
Thank you for purchasing our theme and for reaching us.
Please, make sure you have checked all the server requirements before the installation http://prntscr.com/j0306n
Also, please read our documentation https://www.8theme.com/demo/docs/legenda/#!/installation_upgrade
make sure that all required plugins were installed and activated (list of cush plugins you can find in the documentation), if not, simply upload plugins via FTP https://www.8theme.com/download-plugins/ (https://www.8theme.com/faq/)
then go to Theme Options > Import/Export > Install Base Demo Content button to import posts, projects, products and simple menu. Wait a moment when you’ll see Success message and install version of home page you like https://www.8theme.com/demo/docs/legenda/#!/demo_data_installation
Let us know if you need any further assistance.
Regards