I think it's just a reference to the ExchangeRates webservice, you should be able to access the wsdl of this one. (http://k2learning.azurewebsites.net/ExchangeRates.asmx)
Thank you for your solution.
Yes! It works!
I just found I can access the webservice by VPN.(in China)
But my company server can't use VPN.
However I wrote the service code by myself (takes 2 days😭).
If you could fix the code download link, it would be great.