When opening vectors/EPS files on an Apple computer, you might find that Apple's Preview program opens the file. This is because Preview is set as the default application for opening vectors/EPS files.
Opening Vectors/EPS Files
Preview can open the file in a view-only mode, but you won't be able to edit the file. If you'd like to edit the file, open Adobe Illustrator, select Open and then navigate to the EPS file. This will open the file in Illustrator and you'll be able to edit it as expected.
Set Illustrator as the Default for Vectors/EPS Files
To make Illustrator the default program for vectors/EPS files, select the EPS file, then either right-click and select "Get Info" or press Command+I. In the "Get Info" panel, select Open With, then choose Adobe Illustrator from the list. If it's not listed, select Other and browse to Illustrator's application file location.
You can change this setting for just that one file or click Change All to open all vectors/EPS files with Illustrator.