The client is filing a counter claim and I feel like I’ve been abandoned by levelset, not knowing what to do and not getting needed advice
Since you're in New Jersey - I'll assume you're referring to the AAA arbitration in order to pursue a mechanics lien against a residential property. As you may know, this is a required part of the New Jersey mechanics lien process, so any prospective mechanics lien claimant in NJ will have to file for arbitration. More on that process in this article: New Jersey Residential Mechanics Lien: A Convoluted Process.
Just like other methods of making claims (such as litigation or mediation), arbitration isn't a one-way street. Each party is entitled to put forth their perspective on the dispute, and each party is entitled to assert the claims they feel are appropriate. And, during the mechanics lien arbitration process, both parties are entitled to provide documents and effectively argue why a mechanics lien should (or should not) be granted.
As for how to respond to a specific arbitration counterclaim, the arbitrator should be able to provide information for how and when to respond in accordance with the arbitraton process. But, you'll need to formulate your own responses based on the allegations made in the other party's counterclaim. Of course, having an attorney assist you with that could be useful - and you can begin the search for a New Jersey construction lawyer here: Top New Jersey Construction Lawyers. Note that you can contact those attorneys directly by clicking their profiles then selecting the "Contact" button on the right hand of their profiles.
https://www.vaughanbaio.com/attorneys/colin-m-schmitt/