Upgrading GPU in older build

[Olli73]

Looks like i´ve been out of this for a while. So i downloaded the FreeDOS ZIP, unpacked it and burned the ISO with the OSX-native burning app. When i put the CD into my drive and set the BIOS to boot from CD (in order to make my DOS-Bootstick), it looks like the CD isn´t recognized. What am i missing?
Bear with me please.

 

[P1LGRIM]

What am i missing?

Make sure that Legacy boot is enabled in the BIOS settings.