Apple ID recovery just redirects me to a blank page after I enter my phone number.

I recently got my old iPhone 6 repaired and upon turning it on, I was prompted with an activation lock screen with an old iCloud account.

I had forgotten the password so I went to icloud.com, entered my email, and clicked on the forgot option for password. It asked me for my email again which I entered, then it asked for my phone number. I entered that as well and it just redirected me to the above screen.

At first I thought I had used the wrong phone number so I went back and tried a different one but it said this number is incorrect. So all the details I was using (email ID, phone number) were correct but it just showed a blank screen. I tried this with Chrome on Windows and Firefox on my Android phone, with the same result. Any help is appreciated.