There is no default Web Viewer 14.0 admin id. Web Viewer 14.0 does not store user information. It does not have a user table. Web Viewer 14.0 relies on the CA View repository security to log in users. To login to Web Viewer r14 the user needs to have a valid z/OS credentials for the system where their application server is running.
For the exact rule to create an Admin Id, please see Repository Administrative Authority under Security Requirements in our online documentation.
The security requirements are written for Top Secret. For RACF or ACF2, there are knowledge articles for those two packages giving the security requirements:
ACF2 Commands for Web Viewer 14.0
RACF Commands for Web Viewer 14.0