Hello Ross, I'm Johrelle a fellow Windows/Microsoft user. I'm happy to assist you.
Error Code 0x87E107E3 typically indicates an issue communicating with Microsoft's activation servers.
Ensure you have a stable internet connection. Temporarily disable any firewall or antivirus software that might be blocking the connection.
You can also run the Activation Troubleshooter. Go to Settings > Update & Security > Activation. Click on "Troubleshoot" and follow the instructions.