Class App\Http\Controllers\api\ApiController located in ./app/Http/Controllers/API/Apicontroller.php does not comply with psr-4 autoloading standard. Skipping.
./app/Http/Controllers/API/Apicontroller.php переименовать в ./app/Http/Controllers/API/ApiController.php Script @php artisan package:discover --ansi handling the post-autoload-dump event returned with error code 255
Class App\Http\Controllers\api\ApiController located in ./app/Http/Controllers/API/Apicontroller.php я вижу что у вас Apiпапка в разных регистрах указана, название файла ApiControllerтоже в разных регистрах. Сравните эти два рута и увидите где ошибки Script @php artisan package:discover --ansi handling the post-autoload-dump event returned with error code 255