Most of Dicier's features need you to activate a font feature called 'discretionary ligatures'. The User Guide (currently v1.0) has instructions for doing this in Affinity Publisher (pg31), LibreOffice Writer (pg32), and MS Word (pg33).
If you're using another app, look up its Help docs or user forums for more info. Sometimes apps refer to them with other names, e.g. the Mac plain/rich text editor TextEdit calls them 'rare ligatures'.