This error means that the system fails to validate the installation sources and requires you to restart the installation. It's possible the media might be corrupted in which case you can try downloading from another location to avoid the same copy ISP has cached on their systems.
This can also be due to the problem in your ei.cfg file. To fix the problem, create a new ei.cfg file with the following values:
Now open the installation media and navigate to the sources folder. Paste the ei.cfg file to it. If asked to replace a ei.cfg file, be sure to choose Yes.
Here is a thread as well that discusses the same issue and you can try out some troubleshooting steps from this and see if that helps you to sort the Issue.
Windows Cannot find Microsoft software license terms - During Server 2016 install
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