When installing an AD RMS cluster, the password used to encrypt the server licensor certificate must conform to the password complexity requirement set forth within your organization.

Membership in Domain Admins, or equivalent, is the minimum required to complete this procedure.

To check the password complexity requirements in your organization
  1. Log on to a domain controller in the forest where AD RMS should be installed.

  2. Click Start, point to Administrative Tools, and then click Group Policy Management.

  3. Expand the appropriate forest, expand Domains, and then click the appropriate domain.

  4. Double-click Default Domain Policy.

  5. Navigate to:

    Computer Configuration/Windows Settings/Security Settings/Account Policies/Password Policy

  6. Verify that the password you are entering conforms to this password policy.

Additional reference