If you need to install IIS on several different machines and connect them to one FineReader Server 14 server manager, you would not need the clusters.

If you are still going to use the clusters (FineReader Server 14 Admin guide, Working with clusters), you can do the following:

1. Install Web API component on several machines;
2. Open the ports;
3. Change the location of server manager in Web.config. You would need to type in the IP address of the server manager instead of localhost (default path: C:\Program Files\ABBYY FineReader Server 14.0\FineReaderServerWS\Web.config):

...
<serverManager defaultLocation="localhost" allowCustomLocations="true" />
...