Extract this tarball to /usr/local.  Do not install in /usr.  /usr is under the control of the package manager and should not have data dumped there manually.    Extracting the tarball to /usr might break future installations of a repository fldigi package.

Extracting to /usr/local will provide you with all the files that would have resulted from a ./configure, make and make install.  This will give you menu entries and icons.  It will not install any libraries required for the fldigi application, such as libsndfile, hamlib etc.

You may need to do the extract / install as root or using the sudo command, depending on your particular distribution.

For example:

$ cd
$ mkdir tarballs
$ cd tarballs
$ wget http://www.w1hkj.com/downloads/fldigi/fldigi-3.21.3.bin.tgz
$ cd /usr/local
$ sudo tar xzf $HOME/tarballs/fldigi-3.21.3.bin.tgz
$ cd

Will create a place to save the tarball, download it, and extract to the desired /usr/local directories /usr/local/bin and /usr/local/shared (and sub-directories).