If you see a "Sign-in failed..." message upon trying to log in, it means that an access restriction has been enabled by the account administrator. Depending on the access restriction enabled, you will see one of the following messages:
1) Sign-in failed due to the sign-in time restriction set up by the account administrator. Please contact the account administrator.
You are allowed to log in only within the time set by the administrator. If you need to log in at a different time, contact the administrator.
2) Sign-in failed, because your IP address has not been authorized by the account administrator. Please contact the account administrator.
You can log in only from fixed IP addresses enabled by the administrator. If you have a fixed IP address from which you want to log in, contact the administrator.
3) Sign-in failed, because your device has not been authorized by the account administrator. Please contact the account administrator.
You can only log in on devices authorised by the admnistrator. To be able to log in on a new device, click the request authorisation for this device button below the message. The request will be sent to the email address of the administrator responsible for device authorisation, who will then be able to authorise the device remotely by clicking the button in the email. Alternatively, they can log in to the system from your device and authorise it in the settings > access restriction > device authorisation section.