There are three types of binary Recoll installations:
Through your system normal software distribution framework (ie, Debian/Ubuntu apt, FreeBSD ports, etc.).
From a package downloaded from the Recoll web site.
From a prebuilt tree downloaded from the Recoll web site.
You will only have to check or install supporting applications for the file types that you want to index beyond those that are natively processed by Recoll (text, HTML, email files, and a few others).
You should also maybe have a look at the configuration section (but this may not be necessary for a quick test with default parameters). Most parameters can be more conveniently set from the GUI interface.
If you use a BSD-type port system or a prebuilt package (DEB, RPM, manually or through the system software configuration utility), just follow the usual procedure for your system.
The unpackaged binary versions on the Recoll web site are just compressed tar files of a build tree, where only the useful parts were kept (executables and sample configuration).
The executable binary files are built with a static link to libxapian and libiconv, to make installation easier (no dependencies).
After extracting the tar file, you can proceed with installation as if you had built the package from source (that is, just type make install). The binary trees are built for installation to /usr/local.