Even with the decrypted gp4_1.02_nocd exe file, that you will find on this site using the
FAQ, you will be asked for a CD under Windows 10, if your computer does not have this device.
Then two solutions exist:
1) If you have a portable CD/DVD device you can connect it via USB. It is not necessary to insert a CD/DVD.
2) Install a CD emulation software. I recommend WinCDEmu. Here you need to mount an iso file to activate the emulated CD drive.
petrus' gpaedia files