Plugin has no valid header

Hi,
I installed directly from wp-admin Plugins install.
After installing and activating I get:
“Das Plugin hat keinen validen Header.” which means it does not have a valid header.
I deleted the folder “Trunk” which contained duplicates of everything, then went back to plugins and activation worked.
Please get rid of folder trunk.

https://wordpress.org/plugins/better-facebook-page-box/