I tried to install Universal CSS Navigation Menu using DMXzone Extension Manager but received the

Error installing extension!

The file insertbar.xml is corrupted.

message.

I also tried to manually install the extension by downloading dmxNavigationMenu-1.0.9.zxp file on my local drive and double-clicking downloaded file but DMXzone Extension Manager displayed the same message as soon as it tried to install the extension.

I am using Dreamweaver v18.2

Do you know what's going on there?

Thank you for your assistance.