While Square Enix has released higher version numbers (like 1.5.x), the version is often considered the "golden version" for modding, similar to how many Final Fantasy VII PC players stick to the original 2012 release for mod compatibility.
This usually means the OBB file is missing or placed in the wrong directory. Double-check that the folder path is exactly Android/obb/com.square_enix.FFIXww/ and contains the .obb file. final fantasy ix for android v119 mod repack