You get this message when you have the Foreign File Access extension in your System Folder, but one or more of the access files are not installed.
In order to use the CD-ROM drive that came with your Macintosh computer, you need the following files in your extension folder; Apple CD/DVD Driver (or just Apple CD-ROM depending on the version of Mac OS you have installed); High Sierra File Access; Foreign File Access; ISO 9660 File Access; UDF Volume Access; and Audio CD Access.
If any of these files are moved or turned off using the Extension Manager, the Foreign File Access extension is not be able to locate them and displays the error message "No File System Access Modules could be found in your System Folder. Therefore, the Foreign File Access Software was not installed."