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:
You are allowed to sign in only within the time set by the administrator. If you need to sign in at a different time, contact the 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 sign in, contact the administrator.
You can only sign in on devices authorised by the admnistrator. To be able to sign in on a new device, click the request authorisation for this device link 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. Alternatively, they can sign in to the system from your device and authorise it in the settings > access restriction > device authorisation section.