can not install, but there ís a style.css file

Hi there,

I tried to install the Elen theme in the Wordpress Theme installer. I uploaded the .zip file as instructed. However, something seems to go wrong.
The installer gives the following message:
Unpacking the package…
Installing the theme…
The package could not be installed. The theme is missing the style.css stylesheet.
Theme installation failed.

I checked if this was true. And it wasn’t. There is a style.css file in the .zip file of this template (as can be seen in the attachment). But WordPress doesn’t seem to recognize it… Do you have any idea how I can resolve this issue?

See attachment for the .css file

Good evening

This is not a WordPress theme, its HTML template and it can not be installed in WordPress as a theme