Migration assistant never asks for my Pc account name or password and never gets past security code

What version of macOS is the Mac running?

What version of Windows is the PC running?

Are trying to migrate over your local wi-fi network?

If so, disable wi-fi, connect the Mac and PC directly together using an Ethernet cable, then try again.

for more info and the instructions, see > https://support.apple.com/en-us/HT204087

Wi-Fi fails 99% of the time when doing migrations. These forums have thousands of instances where this has occured, you are welcome to research this if you would like. While transfering relatively small amounts of data works fine using WiFi migrating from a PC to a Mac or Mac to Mac using Wi-Fi fails due to the large amounts of data, soemtimes terabytes of data. Case in point is OP the of this thread.

As a general rule please NEVER EVER use WiFi as it is not designed to have the ban'dwidth to migrate large amounts of data. Please use Ethernet or you can use one of the other solutions to move your data to you Mac.

https://support.apple.com/en-us/HT204087

Two other options if you can't make Migration work according to > https://support.apple.com/en-us/HT204087

1. Contact Apple Support for assistance.
2. Copy the files to a MS-DOS Ex-Fat formatted external drive and manually move them to the Mac.

Great question, please ask them. Most experienced users know this and simetimes in these forums we have to direct folks to what we know WILL work instead of what "should" work.

Rare but is does occur.