I'm really stuck here. How can I design an in game qualitative questionnaire that populates all text into an Excel spreadsheet for further analysis later on

My ideal is to have the player encounter a kiosk or NPC. Interact with the NPC to trigger the questionnaire. Input text via a keyboard (PC only) then submit their answers. The submitted answers will appear in Excel in predetermined categories i.e Question 1 Answer:…Question 2 Answer:… and so on.

Search for dataTable . This is how you’d store text (using Excel). Use structures, to have this text stored. Then parse structure elements. You should do a research about dialog systems . Here is one of them: http://www.nissyokugames.com/hakabanes-ue4-tutorials/tutorial-basic-dialogue-system/

This seems to be in the right direction but this is for a player npc conversation. While the NPC will ask a question, the player will Not choose from a pre s3lcted list. Instead the answrrs must be entered manually and stored in a separate excel spreadsheet

This is where you will create something like widget, where you will input text, that will further be stored into another datatable stricture.

FYI. Complete newbie here. How would I do that? Is there a link with information on that?

this is one of the ways how to input text :

To accomplish your idea you need to research: widgets, dataTables (csv), and SaveGame.
There is a lot of info on that, just use search engines. Good luck!