There are 2 reasons why the theme cannot be uploaded:
1. Please make sure you upload "Installable WordPress file only" from your Downloads ( https://themeforest.net/downloads ) not "All files & documentation"
If there still is a problem with it. Probably it is because theme file is too big for your server and it cannot be uploaded. It should be easy to change in the server panel (e.g. cPanel) or you can contact your hosting provider and ask to increase server settings:
PHP Version 5.6 or greater. PHP settings:
- upload_max_filesize = 64M
- post_max_size = 64M
- max_input_time=300
- max_execution_time=300
- memory_limit = 256M
You can also try to install theme via FTP
1. Download Listivo - “Installable WordPress file only” file from https://themeforest.net/downloads
2. Unzip it. You will see all files
3. Copy the “listivo” folder to the wp-content/themes/
4. Go to the admin panel. Hover over the "Appearance" tab in the left sidebar and click “Themes”
5. Activate Listivo
6. You will receive notification in your administration panel. Click “Begin installing plugins”
7. Activate all plugins. Installation is finished