My friend had the same situation. He could not log in through the application, but he could successfully log in to the site through browsers. Most likely, the problem is in the application version or the installer's file. The program was installed incorrectly on your iPhone, which is why it rejects the login command. Perhaps it's the incompatibility of the app version and your iOS. It happens that not all updates can fully function. I often had problems with sending SMS to my phone number. I had to use a disposable phone number, but it's even more convenient in a sense.
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