Two factor authentication is required for the users with more rights on the website. To enable this first log in to the website. Once logged in you should see your name on the top right (on any screen). Press change my profile or something like that (“Mijn profiel wijzigen”).
Scroll down (waay down) untill you see the part about 2FA and press “Activate 2FA”.
On your smartphone install “Free OTP Authentication”:
Press the QR code button in the app and scan the QR code on the webpage.
You should now see a code on the app on your phone. Enter it.. Well actually the page should be a pretty solid explanation by itself.
Store and backup the recovery codes. But do not use your password manager. Print them, hide them in plain sight under a common name, whatever you want.
You do not want to store these in the password manager because then there is no added benefit of having two factors (because you store both factors in the same, single program). You can also not do this, and if you lose your phone or whatever an admin can recover your account for you.
Anyways, now everytime you log in you have to enter such a code generated by the app! Which is a good thing!