Problem installing AVG Security Unlimited

I have Windows 10 and not a computer expert. Do I have to disable 'Windows Defender' first as I am not getting to the point of a choice to download, I only get the choice to save.  I've checked and I have administrator rights.  Can anyone help?

Hello Mary,
Thank you for reaching us with your concerns. Please be informed that, if you will install AVG Internet Security then Windows defender will be disabled automatically. There is no need to disable  Windows  Defender manually. Yes, you have to save the file at first, after that you will see the option to run the downloaded files. You can follow the simple instruction to  download/install/activate your AVG Internet Security.
Best regards,
Alok.

Hello Mary,
Thank you for reaching us with your concerns. Please be informed that, if you will install AVG Internet Security then Windows defender will be disabled automatically. There is no need to disable  Windows  Defender manually. Yes, you have to save the file at first, after that you will see the option to run the downloaded files. You can follow the simple instruction to  download/install/activate your AVG Internet Security.
Best regards,
Alok.