How I can configure Forms, Web client, Audit trail into NLB ARR?
For web client (and I believe the other products as well), you need to enable session affinity, so that all of a user's requests are routed to the same instance.
Additionally, web client will sometimes need to call a web service on its own instance. This needs to not go through the NLB (because it can end up at another instance), so you may need to have the cluster name in the local hosts file resolving to 127.0.0.1. It can take some fiddling to get it set up, but I know it's been done.
For Forms, you can configure a routing engine cluster using NLB, you can check the document for more information:
And for Forms web server cluster, check Creating a Forms IIS Server Cluster (laserfiche.com).