Can't link to a single collection item

Hi there, I’m still pretty new to webflow and I’m trying to solve as much as I can by myself, but for this issue I need some help. It is really simple: I have a button which I wish to link to a single collection item (a blog post). But when I check my link options, there is no option to link to one of my collection items (page). According to the manual there should be an additional option to link to a collection item, but this is simply “missing” in my case…any solutions?

Here is my site Read-Only: LINK
(how to share your site Read-Only link)