It sounds like you need to unlock the vox-l artifact.
To do that, click the red square on the learntomod homepage, then click to remove the purple filter tags in the corner. vox-l should then be the first thing you can buy -- it's free. Click to buy it, then make sure it's enabled (has a green check mark).
Then go back to the badge you're working on give it another try.
Let me know if it doesn't work.