Hi there- Yes, you can use them wherever you like provided you give attribution according to the license! That can be in a credits section, in a description, or however you need it to be to make it work. I haven't heard of PenguinMod specifically but the assets are designed to be universally compatible with any engine.
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It should be compatible- What I'm seeing says that you can upload images and use them in your Scratch programs. I'm not sure on the specifics of loading and playing an animation, but I would guess it is supported.