If you are following this release, the expected flow is:

To install the Forza Horizon 5 Update v1.671.650-RUNE , you must follow a specific sequence common to RUNE releases. These updates are typically incremental, meaning they must be applied to the correct base version of the game. Installation Steps Verify Version

This is not a "hotfix." The size suggests significant asset replacement or addition, not just tuning values.

Three new-to-Forza vehicles have arrived, each covered in pre-installed livery that looks like Nordic/Celtic runes (a nod to the update name).

Select the option to "Copy contents of RUNE directory to installdir" if it is available to automate the cracking process. Manual Crack (If needed) : If you didn't check the auto-copy box, open the