First off: Welcome to the forum!
Well basically you’ll probably want to just create a UMG widget for a Bluerpint based Quest system.
Whenever the player walks on box trigger one, the text box containing the string “Enter the room” is displayed.
When they enter box trigger two (the room itself), the text disappears and another string replaces it (“Walk to the chair”).
Box trigger three, on the chair, will remove the previous string.
You said you’re new to UE4 so if any of this went over your head, I can post a step by step process for you.
Good luck and never give up,
~ Jason