n [plural]
someone's education, achievements, experience etc that prove they have the ability to do something
credentials for/as
　She had excellent credentials for the job.
　There are doubts over his credentials as a future Prime Minister.
　He spent the first part of the interview trying to establish his credentials as a financial expert.
　Her academic credentials include an MA and a PhD.
a letter or other document which proves your good character or your right to have a particular position
　The commissioner presented his credentials to the State Department.