Have you checked all the server requirements before the installation https://xstore.helpscoutdocs.com/article/60-xstore-theme-requirements ?
Disable all plugins, except Core and WooCommerce, then go to XStore > Import Demos, and go through the import step by step, required plugins will be activated. If you are using a lot of plugins before the import, one of them may cause a conflict or lack of server resources. You will be able to install plugins later.
What demo version do you want to install? WPBakery or Elementor?
Provide temporary wp-admin access, and we will assist you.
According to the ThemeForest license policy, you can use 1 license for 1 project only (dev site, production site, localhost but the same project) – https://themeforest.net/licenses/terms/regular
