Hi Nathaniel. If your plan has been added to a Microsoft 365 group, you can upload files and attach them to tasks through the task details. Otherwise you can save them to your OneDrive or SharePoint storage and share a link to add to the task. https://support.microsoft.com/office/attach-files-photos-or-links-to-a-task-52c688e1-aeb0-4b49-8d78-42984cd553f7

Yes, these documents can be attached to the tasks - either in the Group OneDrive, or via a link to somewhere else.