The latest version of Heroic Library on the mod portal is 2.1.1, so any attempt to install this mod causes the error:

There is no compatible version of heroic-library on the mod portal.

Odd, as I do see https://mods.factorio.com/mod/heroic-library/downloads has 2.1.1

try deleting both this mod and the library mod (if it's in your mods list), confirm to restart the game, then try adding this mod again?

I suppose that's my fault for forgetting to include it in my post. This mod has the following dependency:

heroic-library >= 2.5.2
But the latest version of herioc-library on the mod portal is 2.1.1
Installing this mod is impossible at the moment, because of that.

I did try and uninstall the library to see if that made a difference, but it didn't change anything.

Ahh that makes more sense, should be fixed now

Wow, that was fast! I was able to install it, so it seems to have worked! Thanks!