In the 'Assignment' module, students can only check the assignments submitted by themselves, not the other ones'.

If you would like to make the students be able to check each other's assignments, use the 'Board ' module.

By using the 'Group evaluation' module, you can set it up so that students can evaluate each other's assignments.

Classify groups and create groups in 'Other management > Group Settings' in the left menu of the class page in advance.

Set all the students in the class as one team, and classify the group classification as well.

When registering group evaluation, set the evaluation target to 'team member evaluation' and set the team classification in other settings.

You can check the team evaluation in the 'Instructor's Manual: Team Project(Group Learning) > Group Evaluation' document.