You are trying to install a shopify theme. so you have to do this:
To start the installation, You should unzip package you downloaded from themeforest/elements and you will find another .zip in it, which should be called like your THEM-NAME.zip. Please try to install that .zip.
To install the theme follow the following steps:
- From your Shopify admin, click Online Store, and then click Themes
- Click Upload Theme in the top right-hand corner
- From the Upload A Theme dialog, click Choose File to select one of the .zip files in the Packages folder (mentioned above)
- Click Upload
To publish the theme on your storefront immediately, click Publish theme