You need to input midi chord externally, as its playing it will detect what chord you sent to Reaper and it will go to that region name, select it with the time selection and you have loop enabled on the transport control and it will loop that region until a different chord/part color is entered.
You can drag the C7 from the chord sheet after you unfold it to give the midi that you drag into the start of a Reaper track and import the midi markers, then use the action "markers to regions" and color them with the Instant Track Creator.
To insert a marker on each beat create a custom action > move cursor to next beat > insert marker ,then set a hotkey for it.