Hello Caitlin,
I can understand the inconvenience you have experienced.
I would appreciate if you can provide us the following information to help us understand the issue better.
- Do you have any Microsoft account on your system?
If you download the apps in a local account, you will get a prompt for email and password for the Microsoft Account or setting up a new Microsoft Account in order to accomplish the installation.
However, if you setup a Microsoft Account and then try downloading the apps, you won't get these prompts as the settings would rather sync automatically with the system and apps would get downloaded without getting redirected to the sign-in page.
Hence, if you are in the local account, I would suggest you to refer to the following link to setup the Microsoft Account.
How do I sign up for a Microsoft account?
If you have already signed up for a Microsoft Account earlier but are unable to switch to that account now, then it might be possible that the account is blocked or the password is reset. Follow the steps from the article provided below and check.
*Get back into your Microsoft account if it's been blocked or hacked*
Hope this information is helpful. Do let us know if you need any further assistance, we'll be glad to assist you.