How do I permit a (Not yet classified) program in Windows Defender

I have a Seagate Free Agent external hard drive and want to classify it as
(permitted) as well as my AVG Anti-Virus system... would someone kindly
offer help please.

The help and support entry for:
"Using Software Explorer in Windows Defender"
should explain that.

That only allows the user to view the current situation, it does not allow
the user to change the way that Defender lists a program. The OP wants to
get Defender to permit an item that is currently listed as unclassified. My
understanding is that a user is not able to do this at all.

The beta had an appeal process. I don't know if that still exists.