You do not need an authorization to install Finale. Only after you open it do you need the authorization. So if you are having trouble downloading and installing Finale, authorization is not the problem. Do you know why your computer crashed? If the problem is with the computer (age, OS, malware) then you need to fix that first.

You don't say what kind of computer and what operating system you are using, which is important and why they ask you to include it in the General Instructions for this forum.