It depends on several things:
- does the application support automatic ligatures?
- does the font have the ligatures in question?
- are the ligatures in question "standard" ligatures, or are they perhaps discretionary or historical ligatures? The latter kinds have to be turned on, while the former should be on by default in savvy applications.
When you say "Garamond Pro" are you referring to Adobe Garamond Pro, or Garamond Premier Pro? (Both are from Adobe.)
Neither has cap FF and FT ligatures, but both have "ff" and they might both have "ft" (I'd have to check.)
Regards,
T