You can use this croSSWord .puz file with free Across Lite software for Windows and Mac operating systems. Both of these can be downloaded from the Across Lite download page. Here’s a New York Times FAQ about using Across Lite.
You can also use the puzzazz app on iPhone. Download the .puz file to your iPhone, then when you select the file in your downloads, click on the share button, and there should be a “copy to Puzzazz” option.