Once the app is downloaded on my laptop it keeps asking for a username and password to install. Where do I create a password and what username do I use?
It is asking for your administrative user name and password for your computer. Hopefully you know that (or are working with an IT shop that can install it for you). Without it, you can't install a lot of applications.
IT shop as in my laptop producer?
No. If you work for a company that has people that installs applications and generally maintain your computer, ask them. If you are at home, you need to know your administrative user name and password so you can install yourself. If you don't know tht, maybe a support forum for your brand of Operating System can help.