What you should do is install from the latest version in the repo which is, as of today, held at GitHib. This has support for XE7. The link to this repo is: https://github.com/project-jedi/jvcl
When you get there, follow the instructions. Step 1 is to install the JCL which is also to be found on GitHub: https://github.com/project-jedi/jcl
In fact this is generally how you should install open source projects. It takes time and effort for project maintainers to make installation programs. So you will often find that these installation programs are a little out of date. So, as a general rule, take the latest revision straight from the repo.