The “invalid account” / “authorization failed” / “unauthorized” messages are related to you either entering your password incorrectly or choosing the wrong server.
Please be sure to select mt4.kot4x.com (KOT-Live2 or KOT-Live3) as the server when logging in to a real account. Check your "My Accounts" table for which server you need to choose.
For Demo Accounts, the selection should be KOT4X-Demo (demo.kot4x.com). If the server selection is not the issue, please try resetting your MetaTrader password. This can be done from the "My Accounts section. See the screenshot below.
Click My Accounts.
Click View on the account in question.
Click on the three horizontal dots.
Select Change password.
Click Change Password.
Your new password will be sent to you via email.