Basic Adobe Spark, both the website and the supporting iOS apps, are free. Yep, we said FREE! You can create, edit, share, and tell the world how much you love Adobe Spark. (OK, that last part is optional, but we won't complain if you are overcome with the need to share the Spark goodness).
Spark Premium Features, including the ability to create your own branded content, requires that you purchase a subscription to Adobe Creative Cloud or Adobe Spark.