Your date attribute is of type Date and Time. Any of the FormatDate(Time)(UTC) actions are only to be used when you want to output a date into a string.
If you want to use Date attributes but wish to change the formatting for these attributes, you should check out your Project settings. Under Languages, you can edit your languages. For each language you can specify a custom Date, Time and Date Time format.
The input parameter should be a dateTime object as described here. Also formatDateTimeUTC allows you to enter the format you need as a second parameter.