Child theme for Impacto
That sounds really strange. Are you positive you're looking at the same site/directory?
Your folder structure should look something like this:
However I'm still not sure how to activate the child theme. At the bottom of the installed themes is a message about Impacto child being broken and the following message
The parent theme is missing. Please install the "impacto" parent theme.
If it complains that the parent theme is missing, it's either missing or empty.
If it is there, make sure it's not empty and that it's permissions are also readable (755) by the web server.
All in all, you should have both the /impacto and /impacto-child folders present in the wp-content/themes directory.
*Feel free to PM or email me your cpanel/ftp and wp-admin info and I'll be glad to take a look at it for you.