Acer A20 If the mobile is giving 'Red State' or 'Orange State' warning, then vbmeta patch has to be done to fix it. But if secure boot is enabled, the tools do not allow to overwrite vbmeta. DA Auth File works like magic here. This file temporarily unlocks the mobile's bootloader in a specific state, from where vbmeta image can be written. After that, the mobile boots in safe state and all the warnings disappear..
Acer A20 If you encounter any errors while installing a custom recovery (like TWRP) on your mobile, especially "DA Partition Mismatch" or "Security Boot Enable", then this is a clear indication that you need the correct DA Auth File. This file not only bypasses the protection of the mobile's partitions, but it also tells the tool what the hardware layout of the mobile is. If you use the wrong DA file, the mobile will not boot at all or invalid scatter errors may occur. Therefore, choosing the correct DA file requires research before flashing.