If you have problems with the theme installation the following tips can help.
If you can't install the theme/module or see the error message: 'An error has occurred during the file upload':
This error can occurres when you try to upload theme file which size exceeds 2MB (Prestashop file upload limit by default). Here you can find out your file upload limits: Back-office > Administration > Preferences > Upload quota
So you need to increase the parameter upload_max_filesize in your php.ini file for example to 20Mb. If you don’t know how to do this, write to your hosting provider.