koel/app/Providers/DownloadServiceProvider.php

<?php

namespace App\Providers;

use App\Services\DownloadService;
use Illuminate\Support\ServiceProvider;

class DownloadServiceProvider extends ServiceProvider
{
    public function register(): void
    {
        app()->singleton('Download', static function (): DownloadService {
            return app(DownloadService::class);
        });
    }
}