Have you rented accommodation?
You can find the Wi-Fi code on the flyer inside the accommodation.

Have you rented a camping pitch with private sanitary facilities?
You can find the Wi-Fi code on the shower wall.

Are you camping at Flevo Natuur?
Then you can access the internet in the following ways:

Flevonatuur Free (free Wi-Fi)
Wi-Fi network: Flevo-Natuur Free
Password: flevonatuurwifi