My windows pc keeps saying an error occurred while prepping info for transfer

Here are some steps you might take:

If you have issues moving your data

• Quit all open apps on your PC, then try migrating your content again. For example, you can press Alt-Tab to choose an open application, then press Alt-F4 to quit it.
• If your PC doesn't appear in the Setup Assistant or Migration Assistant window on your Mac, make sure the computers are connected to the same network. You can create a network by connecting a single Ethernet cable between your Mac and PC. If that doesn't help, check for firewall software on your PC and turn it off. After migration completes, you can turn firewall software on again.
• If Migration Assistant doesn’t open on your PC, turn off any antivirus software on your PC. Then try to open Migration Assistant again. After migration completes. You can turn that software on again.
• If you still can't migrate your information successfully, you can use an external drive or file sharing to manually copy important data to your Mac.

Here is the full article to transferring your data from a PC: https://support.apple.com/en-us/HT204087