When you open an assessment that uses evidence, the evidence (if available for that particular student) will show in a link.  Click on the link to see the evidence in a new browser tab:

Review the assessment. Sometimes multiple assessments will be listed as evidence, clicking on each link will open additional tabs.

If necessary, review the uploaded files within the Evidence:

When the “Activity Files” tab is open you can click on the file to open or download it:

Review the evidence, and when finished close the evidence tab, then click on the previous tab to complete your assessment:

When ready submit and complete the original assessment and move on to the next student if necessary.