I cannot download Audacity! I need to convert .AUP to .MP3 tonight! It is for my project I need to pass it tomorrow! Help me please.

You have obviously “downloaded” Audacity (from the Internet) because it is on your computer.
Do you mean that you can’t “start” (launch) Audacity?
When exactly does this error occur?
Which version of Windows are you using?
Has Audacity ever worked on this computer?
Have you recently upgraded anything or installed any new programs?