Hi Yanyan,
The spike trap is included in the itch asset pack. Check the floor tiles sprite sheet, you will find them on the right side. This is a 2 frame animation (spikes out or spikes in).
About the Patreon exclusive content, you need to be a Patreon subscriber to access the extras. As Patron you get new main asset pack releases on Itch at no extra cost + all Patreon exclusive content. I publish exclusive content for the collection on Patreon every month (asset pack add-ons and exclusive creatures). So far there are 76 exclusive creatures, 70 pack add-ons, 33 Icon sets and 8 seasonal asset packs. The dungeon trap add-on is one of the Patreon exclusives, so you have to be a Patreon member in order to get access to it.