Hi Sergey,
Please follow the steps below.
1. Please make sure you have the latest version of WordPress and updated your server PHP version to minimum 5.6.25 or newer.
2. Clean your full database “OR” reinstall a new WordPress with a new database
3. Then install the theme
4. Then install all of the required plugins
5. Then active all of the installed plugins
6. Then import all of the demo data (wait until all of the demo data are imported completely)
Best Regards,
ThemeLooks Support Team