iDRAC 9 can only be connected to LDAPS, so make sure you have that enabled.
The settings then are as follows:
Enabled
Your server address eg. localhost
Your LDAPS port, eg. 6360 or 636
uid=admin,ou=people,dc=example,dc=com
Enabled
Your admin user password
uid
member
(&(objectClass=person)(memberof=cn=idrac_users,ou=groups,dc=example,dc=com))
For the Group Role Mappings, you define groups by their full Group DN
, eg.
cn=idrac_users,ou=groups,dc=example,dc=com