Wherever there is one word of Username, it needs to be changed to "User name".

Ex: 1. The user name and password provided were not recognized. 2. Your token has timed out. Provide your user name and password to continue etc

Also a colon needs to be provided like "User name:" and "Password:"

Wherever "Login" is used as a verb, it should be "Log In" and in case of noun its "Login"