We aren’t lawyers so this isn’t legal advice, but here’s our summary: for the “zero” license you can do pretty much what you want with the sound.

Creative commons has a really nice page explaining them: Depending on the license there are things you can and can’t do with the files. And, we used to have a 4th license, which complicates matters. First of all, freesound lets the user select one of three licenses for his sounds. Well, it depends on what you want to do and which files you want to use. What do I need to do to legally use the files on freesound?

Regarding, I found this under their Frequently Asked Questions If they require attribution, then perhaps ask them directly if there is any specific text that they would like mentioned on your Credits scene for example. Hi think the best advice I can offer would be that if you are in any doubt, contact the author of the assets in question directly and explain how you wish to use them and whether they give their permissions for that.

Unity assets commercial use