Cyclone III support in Quartus 15

According to "Quartus II Software and Device Support Release Notes" on the altera web site, the latest version that has support for Cyclone III is 13.1. You will need to use that version or earlier if you have a Cyclone III board. Note that you can also use the select by device option on the download page to find out what version supports a given device. Some very old parts were never supported by Quartus II and won't be listed.