I think they have different policies and I am sure someone here can explain, but either mixcloud or mixcrate make sure you reference the artist and track names and I think they may get something from that.
Soundcloud have already removed on of my mixes (and I have been there for just a few weeks) for what they said “may” have a copyright issue, which I don’t agree with. Having had some email dialogue with them they took it down due to a complaint from a record label about me using one of their tracks.
It seems Soundcloud take the safe option, which is understandable. I can’t see anyone getting in legal trouble without there stuff being taken down and warnings given first, so I wouldn’t worry too much unless you are claiming other people’s work as your own.
I actually raised a dispute claim against them taking it down, but doing that you have to agree to legal costs etc if they are incurred. I took the risk as I knew it would not come to that, but that is where the risk is likely to be.
May help if you add tracks and links to where to buy them in your descriptions.