“3.10 Auditor’s responsibilities The auditors’ responsibilities are to obtain REASONABLE ASSURANCE about whether the financial statements as a whole are free from MATERIAL misstatement, whether due to fraud or error, and to issue an auditor’s report that includes their opinion.”
As the notes go on to say, reasonable assurance is not a guarantee and the financial statements can – and will – include immaterial misstatements (whether due to error or fraud) when the audit opinion is unmodified. You should find this reinforced in your later studies.