The app caches the list of links so it doesn't have to constantly download the link lists. It will refresh after 15 minutes when going to the home screen.
On the website, If you are viewing the public links, it might take 15 minutes or so for those lists to be updated. There might be so many links submitted by others that your link might appear farther down the list.
The link could also be flagged. Some links are not safe for work and not safe for public viewing. Zholink does what it can to automatically flag and hide NSFW links.
Flagged links are hidden from the public view. You can unhide flagged links by checking the flags in the Allowed Flags section of your profile edit or in the app settings. Note that some links might have multiple flags and you will have to check those flags in order to view those links. In a specific example, ahem, if you intend to view a link to a pornographic site, that link might have the flags porn, NSFW, and vulgar language. You can submit that link back to Zholink to edit and see what flags have been attributed to it.