Here is text from the license that shows that the content is non-exclusive:
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That is correct, however true open-source means making the pack free for everyone, even if they don’t pay. However, you can make the pack free but some kind users may donate (you can do this by utilizing the “Name your own price” feature). The songs on OGA are great, though, so I want to know how the other tracks sound like (I have good hopes)!