(I actually tested in Botania 332, because if I use the latest version I obviously won't get the choice to update 😉 )

• Open an old version of botania
• Create a world with cheats off
• Click download

It's because /botania-download-latest is using the default permission setting which defaults to "ops only," override getRequiredPermissionLevel() to return 0

I don't believe there's a way to fix this, since non OPs shouldn't be able to use the command.

You can make commands runnable for non-ops (see the /seed command)