I can't buy Creative Cloud Plan and I can't even use trial version

I had Creative Cloud Plan for students before, but I missed the date of payment. So, I tried to buy a new plan, but it says about an error after I typed my University details:

Ошибка:

В настоящий момент мы не можем выполнить указанное действие. Примите наши извинения за причиненные неудобства. Мы получили уведомление и стараемся исправить данную ситуацию как можно скорее. Нажмите кнопку "назад" (back) Вашего браузера и повторите попытку позже или выполните другое действие.

Неверный номер:  CAT_000015

and this happens every time when I try to buy a new Plan! Even, I tried different browsers and computers!

I even created two new Adobe ID and tried to use free trial, but it says it's expired! I haven't even open it. An then, I tried to buy Creative Cloud Plan again with different accounts, but the problem is the same as at the beginning. I can't buy anything at all. What the problem?

What can I do?