Because SymbolMT is not a Unicode font, modern macOS relies on the "Apple Symbol" or "Apple Symbols" font to cover the same code points. However, when a document explicitly calls for SymbolMT , macOS will not automatically substitute it. You will see a missing font warning in apps like Microsoft Word, Adobe InDesign, or Final Cut Pro.
First, you need the actual font file. Symbolmt is typically a TrueType Font ( .ttf ) or an OpenType Font ( .otf ). Symbolmt Font Mac Install