Hi Marina

The system is reporting that the Plugin Key is already installed, please can you check if the configuration section "Facebook Catalog Browser" appears in the Zencart configuration menu, as it may have installed already.

If its not there or the contents of this section is blank (e.g. No Plug-in key), it maybe best if you try un-install script and then retry the install script via the Zencart admin.

As always we would remind you to make sure a database backup is taken prior to running any script just in case of any issues.

Bright Software