This is my first time exporting a game to mobile, and when I click project>export, it gives me the following error in the output, in standard white print rather than red letters:

Could not find version of build tools that matches Target SDK, using 30.0.3

I am using this tutorial, and have completed everything before the heading "Version and Package."
https://developer.android.com/games/engines/godot/godot-export

I am using Godot 4.1, so most of the steps are the same with some very slight changes.

This statement in that tutorial is not correct:

A build template must be imported into a Godot project prior to exporting an Android build.

That's only required if you're using a custom template, which may not be needed in your case.

You can export to Android using the default templates that are installed (outside the project) using Editor >> Manage Export Templates...

If you don't need a custom template, disable Use Gradle Build here:
Project >> Export... >> Android >> Options >> Gradle Build

If you do need a custom template, change Gradle Build >> Target SDK to a version of the Android SDK that's installed on your platform. In my case, these are the installed SDK's:

$ ls ~/Android/Sdk/build-tools/
27.0.3  28.0.3  29.0.2  29.0.3  30.0.2  30.0.3