Hi.

So you mean you cannot download, not not install.

What site are you using to download and what, if any, message do you get from Windows to give you any idea that it is blocking the site you are using?

It may not be Microsoft/Windows as such but your set up, including your connection via your IP

Enter the details of the site and I can test it here.

Is it like the warning dialog shown in Why do I get a harmful download message when downloading Firefox on Windows?

If you'd rather use Microsoft Store to have that sorted out for you, here's the button to push to go the Firefox listing and get it from there: https://www.firefox.com/download/all/desktop-release/win-store/

Basically the options are all described in How to install Firefox on Windows