As mentioned in the Assignments help article, compliance tracking is automatically enabled when an assignment is set as Required. While only required items affect compliance, Optional assignments can still be tracked in the same section that Required assignments are tracked even though they don't affect compliance.
Once an assignment is set as required, you have access to the Worker Compliance tab which is available across all the different components that allow compliance tracking:
The worker compliance tab is going to be very similar across all compliance based components with a few minor differences here and there:
You have a basic set of filters and any data displayed can be exported to excel or pdf. In the case of the policies section shown above, I can acknowledge a policy on behalf of a worker or reset a worker's compliance.