Windows 10 Missing file error - 0x80070570

There is source for your ISO (let us say Microsoft). You have a copy.

In OSX Terminal you can get a MD5sum (a file signature) using the following command from your copy...

openssl md5 Windows8.1-64bit.cdr

MD5(Windows8.1-64bit.cdr)= f104b78019e86e74b149ae5e510f7be9

You can ask the source to provide the same information. If they do not match, then your file is corrupted.

Have you verified that the ISO used to create the Windows Installer is not corrupt?

Yes, you can get it from https://www.microsoft.com/en-us/software-download/home using your current Product Key.