Apple keychain / app registration issue

I was trying to help a friend download an app and create an account for it on her iPhone. I figured Apple’s keychain would make it relatively easy. We installed the app and tapped the register button, which brought us to a webpage in the apps built-in browser where we could enter a username. I allowed the iPhone to suggest the password and I tapped “register.” Something happened and the app failed to announce that the account was successfully created. So I tried it again, but for some reason the iPhone was trying to enter my friend’s login password for her phone (obviously not a good idea and it was too short anyway) rather than the password we had just created. I didn’t know what password the phone had created, so I decided to restart the registration process, and this time I made up my own password. Now the app reported that I had entered the wrong password! So finally I fell back on tapping the “I forgot my password” link and it sent an email. Unfortunately email said there was no account, therefore no password to retrieve! This is an important app necessary to manage a financial account. What to do?