Web API (C #) copies external directory files

I have an Api web in C # .net framework. In this application I have a method responsible for copying some files to a local directory, where I have my frontEnd. The problem I'm having is that my web service (after being hosted) can not copy files from the network directory, which was not the case when the application was local. Is there any configuration I have to do on my IIS server so that the files are copied the same happened on the local server? if application help does not return error messages when trying to copy files.