Similar to ACC, Fusion Manage should allow users to markup a PDF and download the file with every markup. This is useful for companies dealing with vendors who need to be able to download the PDF with all markups and don't have access to it any other way.
Other Autodesk tools are using this capability and there is redlining capabilities already within FM for DWF and DWG file types. This request is not uncommon for FM users, as there is an idea submitted for it going back to 2019. (https://forums.autodesk.com/t5/fusion-manage-ideas/dwf-or-pdf-markup/idc-p/9348663#M3992)