Hello Tadas_Andrulis,
Thanks for using our theme.
In case if automatic plugin installation fails (as a rule it is because of your server settings), you can install them manually via your Dashboard: Plugins > Add New > Upload Plugin > Browse plugins archives. Or via FTP, by uploading and extracting the plugin zip files into wp-content/plugins folder. You can find the zip files for plugins installation here – https://www.8theme.com/downloads/
If you need any further assistance, let us know what demo version (Elementor or WPBakery) do you want to import and provide FTP access also.
Regards