The application "Garageband" can't be opened error message?

I just downloaded Garageband for the first time on my Macbook Pro, and I'm having some issues getting it to open. When I first try to launch it, I get a dialogue box say "macOS needs to repair your Library to run application" (first time I've ever seen this), then after I enter my password it immediately pops up saying that Garageband can't be opened. I've never installed or ran Garageband before, and so I'm a little confused on why this would be happening.

I've used Ableton, a different DAW, for a long time, and have some third-party plugins installed that I use on there. Could those be causing the problem? I've tried moving all of the AU plugins out of the folders but that still doesn't work.

Thanks for any help!