Hello cyrilp,
In the following article you can find the instructions on the setting up the network processing:
https://agisoft.freshdesk.com/support/solutions/articles/31000145918-how-to-configure-the-network-processingThe important thing is that each processing node requires a separate Professional edition license in order to be used simultaneously.
Nodes do not need to have extra large hard drive, as it wouldn't be utilized for the processing (unless there's insufficient RAM and a disk swap is used), so it's better to have at lest 32 GB RAM installed on the nodes (64 GB is preferred).
Fast connection between the nodes and network storage (where the source data and project files are stored) is important and at least 1 GBit is required. Using 10 Gbit connection is not obligatory, though, as 1 GBit in most cases will be sufficient.
Most of the general processing tasks support fine level task subdivision, i.e. can be processed on multiple nodes simultaneously, however, there are some that will be processed on the single node only (Build Mesh from the dense cloud source, Build Texture - from the main Workflow operations).
The performance benefit will not be exactly N times (when N nodes are used) compared to the single node processing and will be lower than that due to the additional data transfer operations and certain sub-steps that are not parallelized.