How do I create, and setup, various groups within NPM but without using AD?

We (local ISP) use NPM through our N0C department, not our I.T. department.  We do not use AD within the N0C.

I would like to be able to create various user groups/roles, for ease of use and efficiency.

The only thing I have found so far MUST be used with AD, which again, we do not use.

I would like to think NPM would allow us to accomplish this.  However, I feel NPM is simply taunting me with the feature(s) I require/request, as they are present, yet unusable in the simplest form.

Thanks,

-Will