Non commercial use

Free and for pay assets come with a licence. The licence determines what you can do with the asset. Non-commercial, or commercial use is irrelevant here.

Adobe has a Free Collection of more than 900,000 assets, but it doesn't seem to include any audio tracks. You can get some audio tracks for free with a Trial susbscription, but that's only possible for a very short time during the trial period. Thereafter, the trial converts to an annual plan, invoiced monthly.