This MacBook Air 2017 has been freshly installed with Mojave. I wiped the disk before doing so.
After that, I went on to the App Store to download iMovie... but it won't download! The error message displayed above, and "cancelled" inside the popup box, was all the info given. What could this be? I tried deleting App Store preferences, cookies, restarting the computer, changing DNS to 220.127.116.11, changing wi-fi, but none worked.
Also, the download button was a cloud with an arrow, not the usual "GET" button.
I have signed in with the same Apple ID as last time- both for my iCloud and App Store.
EDIT: Even other apps won't download. This problem is not specific to iMovie.