I just installed the Ceevee-Skeleton and have no clue how to get these modal link-boxes working.
Just as in the demo the portfolio items don’t expand by clicking on them and don’t link to the given URL.
The portfolio twig gets the link from the frontmatter:
Copy file jquery.waypoint.js from the zip into /themes/ceevee/js and rename the file into waypoint.js
Unfortunately, if you do this in theme CeeVee itself, your changes will be overridden when CeeVee gets a new version (not likely though). You should therefor create an inheriting/child theme of CeeVee and make changes in your own child theme.