** Unofficial Patch and Tools:** Alternatively, you can try using third-party tools or patches, like the " Character Unlocker" or "SFxT Character Unlock Tool" (be cautious when using these, as they might not be officially supported).

Capcom released an official patch for Street Fighter X Tekken on PC, which includes various bug fixes, balance changes, and... character unlocks !

Some users reported that Patch 1.02 (not 108 specifically, but close!) or later versions unlock all characters. You can try updating your game to the latest version.