In general, Client (end-user) accounts in WHD can store basic info about the users (username/first name/last name/telephone/email/location/department/company) but you can also create any Client Custom Fields that you'd like to in order to store other info, like Role for example.
If you have an LDAP connection configured in Active Directory, you can have a sync to periodically run and pull any new users in AD and create WHD Client accounts for them automatically. You can map over whatever AD fields you'd like to the custom fields.
Usually, the Client record would not exist first in WHD - it would be created in AD, then be synced in.
You may wish to check out this other thread which talks a bit about setting up an onboarding/new hire process in WHD: