This is a common issue that occurs during WordPress theme installation.
The reason you are getting this error message is that you are trying to upload the incorrect file, that is, you are trying to install the entire .zip file that you downloaded from our website. If you want to install a theme, you’ll need to extract the downloaded .zip file first, install a parent theme, and then install a child theme. Keep in mind that the child theme name is the name of the theme you’ve purchased, while a parent theme name doesn’t necessarily have to be the same as the child theme name; for example, Coleta theme’s parent name is Deppo.