How can I cancel the instruments download?

I used the "Restore Sound Library" function from Garageband 10.0.3's menu. A split-second before clicking the "Download" button, I realized that the files were over 5 GB. I do not have this much room on my computer! (Room on my hard drive has been a recurring issue and I have already gone through everything I can get rid of... in case someone wanted to suggest that.)

Now there is no way to cancel the download. The download window even states that if I quit Garageband the download will resume when I re-open it. I can't quit Garageband forever because I am using it! I have already tried searching for answers to this issue, and found none.

Is there a way to force this download to cancel? I don't want to have to deal with the slowness of a full hard drive. If not, where do these extra instruments download to (so I can delete them once the download is complete)?

Thank you!