Many of the files downloaded from Designbundles come as ZIP files, this a common way of distributing multiple files which are contained within a folder and the files within are 'compressed' which can save Hard Drive Space.
This tutorial will walk you through opening the .ZIP files on your Mac. The file used in the tutorial is Cute Forest Collection.
1. The Download
When you first download the ZIP file from Design Bundles to your Mac, it will appear in your downloads folder (or another folder if you have specified a different folder in your browser).
To 'Unzip' the file you can either double click on it, or right click and go to 'Open With' followed by 'Archive Utility' which should be installed on your Mac by default.
3. The Unzipped Folder
After the unzipping process, you will notice a folder has been created, this folder contains all of the elements that were included in the ZIP folder.
4. Navigating the Folder
You can now navigate through the folders to find the elements you wish to use in your design and open them in the software you wish to use them in.
At this stage you can use the elements in your required software.