There is also an example series on their channel with an endless runner.
Basically what you need is:
HUD User widget with the bar item
HUD User widget for displaying the picked up item amount, and overall time.
And maybe another for the end score screen, where you calculate pickup amount with time, and output the result.
To pickup an item set a bool value for (picked up item), and an integer for the amount, save this on the player controller, or on the GameInstance (if you going to destroy the player character upon death/time out, instead of transforming his location, and or hiding the model).
The pickup mechanic could work like this:
When the player capsule overlaps with the pickup item (requires to set Enable overlap events, for Player capsule, and the pickup item collision sphere), set the bool and integer, then destroy the item and spawn an emitter effect at that location, and a pickup sound.
The pickup item, create a blueprint, add a sphere or box collision, and then some fancy static mesh, here you also could add a rotation, for rotating coin, and some effect like glowing.