You need to meet the technical requirements for the Site1 documents.

[Reference:, https://docs.microsoft.com/en-us/microsoft-365/compliance/apply-se HYPERLINK "https://docs.microsoft.com/en-us/microsoft-365/compliance/apply-sensitivity-label-automatically?view=o365-worldwide#how-to-configure-auto-labeling-policies-for-sharepoint-onedrive-and-exchange"nsitivity-label-automatically?view=o365-worldwide#how-to-configure-auto-labeling-policies-for-sharepoint-onedrive-and-exchange, , , ]