I will summarize our conversation in the TestProject chat here as well:
"I investigated your issue and I found that your website checks if the URL that its currently in, is the same as the top of the window.
Since we are presenting your website inside an iframe, the URL is different and your website has a logic of changing the top, which is our iframe. You cannot access to the iframe and this throws an exception.
We are currently working on a new recorder that won’t present your website inside a recorder, so this issue should be gone by then. At the moment, you can create the elements in the login page manually to complete the login flow. Although it won’t work in the recorder, it will work once you will run it from outside the recorder."