Há FAQ oficial em seu site explicando:
We currently only provide 32-bit builds. In order to run these on a 64-bit system, you will have to install the 32-bit compatibility libraries provided by your distribution. For example, on Ubuntu, install the package ia32-libs by running sudo apt-get install ia32-libs from the command line.
O Fedora está fornecendo pacotes semelhantes que podem ser instalados usando
sudo dnf install alsa-lib.i686 alsa-plugins-oss.i686 alsa-plugins-pulseaudio.i686 alsa-plugins-pulseaudio.i686 arts.i686 audiofile.i686 bzip2-libs.i686 cairo.i686 cdk.i686 compat-expat1.i686 compat-libstdc++-33.i686 cyrus-sasl-lib.i686 dbus-libs.i686 esound-libs.i686 fltk.i686 freeglut.i686 glibc.i686 gtk2.i686 imlib.i686 lcms-libs.i686 lesstif.i686 libacl.i686 libao.i686 libattr.i686 libcap.i686 libdrm.i686 libexif.i686 libgnomecanvas.i686 libICE.i686 libieee1284.i686 libsigc++20.i686 libSM.i686 libtool-ltdl.i686 libusb.i686 libwmf-lite.i686 libwmf.i686 libX11.i686 libXau.i686 libXaw.i686 libXcomposite.i686 libXdamage.i686 libXdmcp.i686 libXext.i686 libXfixes.i686 libxkbfile.i686 libxml2.i686 libXmu.i686 libXp.i686 libXpm.i686 libXScrnSaver.i686 libXScrnSaver.i686 libxslt.i686 libXt.i686 libXtst.i686 libXv.i686 libXv.i686 libXxf86vm.i686 lzo.i686 mesa-libGL.i686 mesa-libGLU.i686 nas-libs.i686 openal-soft.i686 openldap.i686 pam.i686 popt.i686 pulseaudio-libs-glib2.i686 pulseaudio-libs.i686 pulseaudio-libs.i686 qt-x11.i686 qt.i686 redhat-lsb.i686 sane-backends-libs.i686 SDL.i686 svgalib.i686 unixODBC.i686 zlib.i686
(todos eles podem não ser necessários para o seu pacote. Origem das Pergunta do AskFedora )
Então você deve ser capaz de instalar e executar o pacote instabird de 32 bits.