An Invalid Account error on the MT5 simply means that you are most likely entering the wrong login data (account number or password)
If you are in doubt, you can always check your account number or change your MT5 login password from your client area.
You should also make sure that you are using the correct server, which is
If your account has not been active for a long period of time, it may have become archived. To check this, you can contact our support team (see link below)
If you have any further questions about this or any other issue, feel free to contact us at any time! Our support agents are standing by to assist!