Hi Jules,
Thank you for reaching out. Be sure out theme is compatible with the last version of WordPress.
To update your theme, you can download and install the Envato Market plugin on your WordPress site.
Once the plugin is installed and activated, go to “Envato Market” in your admin menu and follow the instructions under “Activate Envato API Connection”.
When this is done, you will see your purchased themes under the “Themes” tab and you should be able to update your theme from there by clicking the “Update available” button.
Cheers,