If the Client Manager is down, you have no Tidal client. Period. There is no Fault tolerance for the Client Manager provided by Cisco.
We plan to implement two Client Managers for this reason with a load balancer in front. This will give us fault tolerance.
There is no charge from Tidal for additional Client Managers. You can install as many as you want. Of course, you will need a server and database for each, so you will have that cost.