Next / Previous pagination on folder of pages

I’m trying to add “NEXT” and “PREVIOUS” pagination to the bottom of pages that are in a in a specific folder called “Portfolio”. Been trying to figure this out for a while now.

Is there a simple way to go about this and add the pagination on the bottom of each individual portfolio page.

The portfolio pages are linked to the portfolio layout.

Current folder setup:

layouts:
-default.erb
-portfolio.erb

portfolio:
project-name.html.erb
project-name.htm.erb
project-name.htm.erb