Yes, the illustrations you find on scale are literally "royalty-free vector illustrations for commercial use" - absolutely free and no attribution needed. Academic, personal or commercial use, doesn't matter - feel free to use Scale's illustrations! The only condition is to not use our illustrations to resell, or repackage. Basically don't duplicate Scale or create a competitor product. Otherwise,
![Royalty free Vector Illustrations for Commercial Use | Scale](https://cdn-ak-scissors.b.st-hatena.com/image/square/e7e6ac370db2f2576d420b1b101d5fcbcc8d9fc9/height=288;version=1;width=512/https%3A%2F%2Fflexiple.com%2Flink-preview.jpg)