All content downloaded from the internet that you use within your creativity must be provided with a regular license for commercial use, whether they are music tracks, video clips, photos, graphics and so on...
Using content downloaded freely from the web (Google, Youtube and other online sources) is not allowed, even if they have the "copyright free" indication.
This is because copyright legislation is complex and these terms very often do not reflect the requirements necessary to have the effective permission to use the content for commercial purposes.
All the content that you find on the internet in fact are made by someone - the author - who has rights on such contents and it is necessary to ask his permission to use them.
If you have any doubt about the content allowed, you can contact the Zooppa staff by writing to email@example.com.
We will give you all the necessary support to understand how to best prepare your content.