The cm-x86-13.0-rc1 is a porting of CM 13.0 to the Android-x86 platform as the BSP. Based on the Android-x86 6.0-r1 and the latest CM 13.0, it includes almost all the features from the two open source projects.
This release contains two files. One is the 32-bit x86 ISO and the other is the 64-bit x86_64 ISO. Both can be boot from legacy BIOS and newer UEFI firmware. You can choose one of them depends on your devices. In doubt, try the 32-bit ISO for legacy BIOS devices and 64-bit ISO for UEFI devices.
To use an ISO file, Linux users could just dump the it into a usb drive to create a bootable usb stick like
dd if=cm-x86_64-13.0-rc1.iso of=/dev/sdX
where /dev/sdX is the device name of your usb drive.
Windows's users can use the tool Win32 Disk Imager to create a bootable usb stick.
Please read this page about how to install it to the device.
repo init -u git://git.osdn.net/gitroot/android-x86/manifest -b marshmallow-x86 -m cm.xml
repo sync --no-tags --no-clone-bundle
Read this page for how to compile source code.
The cm-13.0-x86 branch is mainly ported and maintained by Jaap Jan Meijer.