The Custom Synchronization StackPack is a StackPack that is meant to ease the setup of a custom topology synchronization. It works well with agent checks and can be a first step before making a StackPack.
The Custom Synchronization StackPack is meant for integrations that include a topology aspect. If your integration only has telemetry then you do not need this StackPack.
The easiest way to get started is to follow the push-integration tutorial.