how can i get to louidon mega apt hotel from baiyun international airport?

Well, you can take Shuttle Bus Night Line 5 to Haizhu Square (operating till the arrival of the last flight), and then you can take a taxi to your hotel.
Or after arriving at the square, you can walk north along GZ Qiyi Rd for 5 minutes and turn east to Danan Rd. Then walk east for 10 minutes and turn north to West Fuxue Street, you will see your hotel.