Generally speaking, samples from sample websites or found within DAWs are fine to use within your music (unless stated otherwise) and do not have to be declared as Samples when submitting to our catalogue.
However, sampling any audio that is copyrighted such as an existing vocal from a well-known track, needs to be disclosed when submitting to sync. It’s advised to seek permission from the original sample owner to include in your audio or to simply not include any uncleared samples in your music at all.