Good Day Rj_MS,
My name is Carlo, I am also using Windows 10 pc and community member like you. Let us work together to sort this out.
No need to disable the Windows Defender, and the file you are downloading is a safe, feel free to download ISO without turning it off.
I hope the information above helps. Please let me know how it goes.
Have a wonderful day ahead and stay safe.
Sincerely,
Carlo T.