I have previously installed this successfully on a Raspberry Pi 3 which recently died. I have tried unsuccessfully to install on my new Pi 4 4GB a few times. I have updated, upgraded, did a dist-upgrade, and I get the same results. I even tried to put the SD card from the Pi 3 into the Pi 4 as I read that it should work, but no go.
If the version you run (./config.guess) is already up to date, please
send the following data and any information you think might be
pertinent to <
config-patches@gnu.org> in order to provide the needed
information to handle your system.
config.guess timestamp = 2008-01-23
uname -m = aarch64
uname -r = 4.19.127v64
uname -s = Linux
uname -v = #1 SMP PREEMPT Fri Jun 12 22:09:51 CEST 2020
/usr/bin/uname -p =
/bin/uname -X =
hostinfo =
/bin/universe =
/usr/bin/arch -k =
/bin/arch =
/usr/bin/oslevel =
/usr/convex/getsysinfo =
UNAME_MACHINE = aarch64
UNAME_RELEASE = 4.19.127v64
UNAME_SYSTEM = Linux
UNAME_VERSION = #1 SMP PREEMPT Fri Jun 12 22:09:51 CEST 2020
configure: error: cannot guess build type; you must specify one
Citadel Easy Install is aborting.
The last few lines above this message may indicate what went wrong.
Linux Debian 10.6( 4.19.127v64 aarch64)
I hope this helps.