Hi Vertika,
The dataview control bar exists in versions of Mendix prior to 6.7 and the dataview footer exists in versions 6.7+. It looks like you're using 5.21.1 which still has the dataview control bar which only allows for button widgets. If you were to upgrade your project to Mendix version 6.7+ you would be able to add any widget to the (now called) "footer" section.
Documentation on the two can be found here.
Best,
Matt