Let's check under below:
1. Use ZArchiver app (you can download on google play store free)
2. Go to "sdcard/android/obb/com.first....fts15/"
3. Rename the obb file to ".zip"
4. Select view file inside
5. Go to "data/models/player/textures/"
6. Click (+) button on right bottom, then select all new boots you have been saved.
7. Wait a process, and go back.
8. Don't forget to rename like original the ".zip" file to ".obb"