Having problems with WP Cost Estimation & Payment Forms Builder

Hello @loopus
I’m trying to install your amazing plugin bt I can’t:
it says this:

Unpacking the package…

Installing the plugin…

The package could not be installed. No valid plugins were found.

Plugin installation failed.

Can you help me?
I’m using last updated wordpress + elementor

sorry, fixed: I had to install the file WP_Estimation_Form that is inside the zip.