Once finished, navigate to the output folder (often sd:/gm9/out ) and try installing that decrypted file through FBI.
If you're still running into trouble, updating FBI to the latest version can often resolve generic installation errors: failed to install cia file 0xd8e0806a
A corrupted download or a bad dump of a cartridge can produce a CIA that the 3DS’s installer cannot parse. This often triggers the error immediately at 0% or 1%. Once finished, navigate to the output folder (often
on Mac/Linux to verify the card isn't a "fake" or corrupted drive. 3. Use the Correct Installation Method If you are using a physical 3DS, the Hacks Guide Wiki recommends using the application: Navigate to -> your CIA folder. Select the file and choose "Install and delete CIA" failed to install cia file 0xd8e0806a