Both of these sites have free apps in the app store that anyone can download and install. When you first try to use the app, you will be prompted to login with your login and password. To create a login you need to register at the websites below.
The links below take you to DoIT web sites for Office and AMI (account managment interface).
If for privacy or security reasons you wish to create an Itunes account that is not linked to your credit card, the info below from Apple will help you set up an iTunes account not linked to a credit card. Then you can add credits from an iTunes gift card for purchasing apps.