Jake, premium membership is not required for the challenge, but premium membership will make it much easier to learn.
In our last challenge, one of our basic members was able to learn a premium member song by watching the performance video and other member’s submissions: https://rockclass101.com/forums/topic/participate-in-the-may-2017-member-challenge-classical-ukulele-challenge/page/7/#post-11776
Unfortunately, you will need to play our complete arrangement to qualify for the giveaway.