Google designed Flex to be installed via a dedicated tool to ensure hardware compatibility (validating boot flags, UEFI/BIOS modes, and TPM chips). The official recovery.conf file points directly to a raw bin file (which is an ISO-compatible image).
To get the best performance, your device should meet these minimums: : Intel or AMD x86-64-bit compatible device. RAM : 4 GB or more. Storage : 16 GB internal storage. chrome os flex download iso 64 bit exclusive