There is a tutorial to activate the data folder mode.
HERE!!
https://gamebanana.com/tuts/14613
VIDEO INSTRUCTIONS ACTIVATING DATA FOLDER MODE:
https://gamebanana.com/tuts/14924
INSTRUCTIONS FOR ENCORE OR MANIA VERSION:
For this mod to work, do all of the above plus the following actions: Extract the rar file, then move the "images" folder to your new "data folder".
THIS MOD IS FOR PC. NO FOR ANDROID, NINTENDO SWITCH, ETC XD
Instructions to change to the alt background. (OPTIONAL, IF YOU LIKE IT)
Extract the "images_the_overhaul_update.rar" file included below in the downloads, then move the folder to ("your sonic 3 air folder"/data/) and paste it.
USING MANIA FONTS (LETTERS MANIAFIED):
EXTRACT THE MANIA FONTS LETTERS RAR FILE AND PASTE THE PNG AND JSON FILES TO "YOUR SONIC 3 AIR FOLDER/DATA/FONT" AND PASTE THOSE FILES :)
FIX NUMBERS GLITCHED IN TIME ATTACK:
Download the file "sonic3_fontC_fixed_numbers.rar" included in downloads section and paste the png image to "font" folder
ADJUSTED FONTS:
Extract the "adjusted_font.rar" file and paste the JSON file in "Sonic 3 AIR GAME FOLDER"/data/font. REPLACE IT
COMPATIBLE WITH:
Pause Menu Emeralds & Ring Chain mod by Bandway