You may use the downloaded piece or the piece sent as a pdf file privately. For a public performance you need the consent of the authors. Registration of the programme of the performance with the relevant authors’ association (GEMA, AKM …) is necessary to comply with copyright law. All rights to the music belong to the composer. Lyrics (e.g. in songs or plays) may affect other copyrights. This is the responsibility of those responsible for the performance.
You do not acquire any rights to the audio samples. They may not be used, recorded, reproduced or otherwise exploited beyond listening to them on the website.