You've received a notification and you're ready to review and add comments.
As a reviewer you'll pin issues to the document to provide feedback and add markups. You'll see issues raised by other reviewers too and can provide feedback as required.
You'll be able to see issues raised by parallel reviewers if issue visibility is enabled for that review. Otherwise you'll see those issues after the step is completed.
If you are the lead reviewer you'll choose a review outcome to complete the step.
You'll see all review steps that require your action.
Once all steps in a review are completed and the review was configured to assign issues automatically, the issues will be assigned to the originators to respond to. Otherwise, the process owner can manually assign the issues.