[dpdk-users] Compiling fails

[Saint Michael]

I downloaded dpdk-20.02.tar.xz and run source usertools/dpdk-setup.sh but
the script fails to install with "Installation cannot run with T defined
and DESTDIR undefined"

I also need to build rtr_kni.ko, for my kernel 5.6.12-1.el7.elrepo.x86_64,
but the module that I need to compile, "rte_kni.ko" is not available, all I
see is
 find -name "rte_kni*"
./lib/librte_kni/rte_kni.h
./lib/librte_kni/rte_kni_version.map
./lib/librte_kni/rte_kni.c
./lib/librte_kni/rte_kni_fifo.h
./lib/librte_eal/linux/eal/include/rte_kni_common.h
./x86_64-native-linux-gcc/build/lib/librte_kni/rte_kni.o
./x86_64-native-linux-gcc/include/rte_kni.h
./x86_64-native-linux-gcc/include/rte_kni_common.h

kindly help me understand what am I doing wrong? My goal is to pin two
network interfaces to a single core each, to accelerate packet processing.
Philip