It's CC0. Release your fixed models on itch.io. Or at least make a youtube video or something showing how you did it.
If you don't, I will. It's free real estate! Edit: No I won't. The included FBX files may be fraught with legal peril! See below:
Edit: Upon closer inspection, the blend file has no animation setup for any of the characters, but the individual fbx files appear to contain animation data. I'll try importing them back into blender and see what happens.
Edit 2: I'm seeing a Mixamo NLA strip in here. Is that just intended to allow for compatibility with Mixamo out-of-the-box? Or does it imply that the rig was originally authored by Mixamo, and thus may not be compatible with the CC0 lisence?
Edit 3: Apparently Adobe owns Mixamo? And their TOS prohibits distribution of "character or animation raw files." Whatever that means.
I am not a lawyer, and this is not legal advice, but I'm done examining this asset for educational purposes. Too dangerous to touch.