I suspect you didn't run you migration command correctly.
Try php artisan migrate --bench="flarum/core"
instead of php artisan migrate --package="flarum/core"
Here are the steps for setting up your DB from the beginning. After you have setup your L4 and workbench folders, run these commands
```
php artisan migrate --bench="flarum/core"
php artisan db:seed --class="Flarum\Core\Support\Seeders\DatabaseSeeder"
```
This should work for you.
Cheers!