Transferring files from Windows external harddrive unexpected error has occurred

I'm setting up a new Mac and looking to transfer files from a PC. The PC has died and the files are on an external harddrive (Seagate). Everything I google tells me I should just be able to drag and drop or copy and paste the files to the new MacBook but everytime I do I get "The operation can't be completed because an unexpected error has occurred (error code -50)." and only a few of the files are copied. What can I do?