Hi Melvay, You can download the ITV Player app from here.

Your issue with buffering could be down to a number of issues, please make sure you have a good internet connection, its recommended to have atleast a 10MB connection. You can test your connection speed by vising here

Other issues which may cause buffering include your connection to your router, connecting your device via ethernet cable will give you the best connection, although wifi works fine as long as the device isnt positioned too far away from your router, you may also suffer buffering if the server you are streaming from is lagging due to the amount of people trying to view the same stream at the same time. If you need further assistance please feel free to ask.