Since the A37m is an older device originally running Android 5.1 Lollipop , "fixed" ROMs usually aim for stability over new features:
You cannot flash a custom ROM on a locked bootloader. You may need specific Oppo Unlock Tools or fastboot commands. oppo a37m custom rom fixed
Flashing wipes everything. Move photos and contacts to a PC. Charge Battery: Ensure the phone is at least 60% charged Unlock Bootloader: Since the A37m is an older device originally
After flashing,