Hi,

The problem is that you've uploaded the wrong file.

If you downloaded the "All files and documentation" package from ThemeForest, please extract the zipped package downloaded from ThemeForest to your desktop. In the extracted package you will find soledad.zip which is the WordPress theme file.

If you downloaded "Installable WordPress file only" from ThemeForest, you just need to use this file for your installation.

For more information, please read the document here: https://soledad.pencidesign.net/soledad-document/#import-demo

Regards,
PenciDesign.