I am trying to install Image Scale Plugin but I'm getting warning message. Am I doing something wrong or there is something wrong with the zip file?
You are getting this message on plg_content_image_scale install:
JInstaller: :Install: Can't find Joomla XML setup file.
Unable to find install package
Don't worry because ContentBuilder Image Scale Plugin is installed to ContentBuilder/Joomla! right away on the ContentBuilder install.
You can simply start using it right away.
That applies for other plugins from ContentBuilder installation folder - com_contentbuilder_joomla30/admin/plugins