I’m looking for a solution that will authenticate but also let me know current user count. The user logging in will only be authenticated if there is an available user license. Is this functionality available?
There is no built-in functionality that would address your requirements purely through configuration. However, there are enough extensibility points for you to be able to accommodate that. In particular, you can create a custom rule that rejects every authentication attempt afters the number of licenses have been exhausted. Rules are mostly Node.js code so you can call external systems that would keep track of active licenses being used and reject authentication attempts based on that.