I have a customer in China who is unable to download the pdf files I sent her using send and track, no one else has had an issue iso is it due to her being in China?

I have shared files with a client in China using send and track and she can view them but not download them please help! I have tried online chat who kept me on for over an hour and didnt help other than asking me questions I even sent them pics as they didnt seem to understand what send and track actually is. I have tried calling but get disconnected, I have tried twitter who have directed me here.