In essence, these settings tell Word, Excel, PowerPoint, and Visio: “When you encounter a file saved in [X format], do not let the user open it—or, at the very least, do not let them save to it.”
The actual error depends on the Office version, but the fix is always the same: The IT admin must either unblock that file type globally, or the user must use a third-party tool to convert the file to a modern format. Look closely at the File Block Settings dialog. For each file type, there is a third option nested in the dropdown: "Open selected file types in Protected View" (instead of blocking them outright). file block settings in the trust center
Use PowerShell to scan network shares for .doc , .xls , and .ppt files. Identify who owns them and when they were last modified. In essence, these settings tell Word, Excel, PowerPoint,