Permission errors backing up entire system using rsnapshot over local server

EDIT: the solution to this problem is the marked solution underneath + enabling PermitRootLogin without-password in /etc/ssh/sshd_config I'm trying to backup my entire system to my local server, but I even though I'm running rsnapshot as sudo, I get permission errors in /var/, /etc/ and /usr/. Is there a way to fix this? If there isn't, what's my best option to backup my system to my local server? This is my rsnapshot.conf

config_version	1.2

###########################
# SNAPSHOT ROOT DIRECTORY #
###########################

snapshot_root	/home/gisbi/backup/

cmd_cp		/bin/cp

cmd_rm		/bin/rm

cmd_rsync	/usr/bin/rsync

cmd_ssh	/usr/bin/ssh

cmd_logger	/usr/bin/logger

cmd_du		/usr/bin/du

#########################################
#     BACKUP LEVELS / INTERVALS         #
# Must be unique and in ascending order #
# e.g. alpha, beta, gamma, etc.         #
#########################################

#retain	hourly	24
retain	daily	7
retain	weekly	4
retain	monthly	12

#logs

verbose		5

loglevel	4

logfile	/var/log/rsnapshot.log

lockfile	/var/run/rsnapshot.pid

ssh_args	-p 22

#exclusions

exclude		/dev/*
exclude		/proc/*
exclude		/sys/*
exclude		/run/*
exclude		/var/tmp/*
exclude		/var/run/*
exclude		/tmp/*
exclude		/run/*
exclude		/mnt/*
exclude		/usr/portage/distfiles/*
exclude		/lost+found
exclude		/home/gisbi/Storage
exclude		/home/gisbi/.local/share/Trash/*

#location

backup	gisbi@192.168.1.15:/		popbackup/

EDIT: errors look like this

rsync: [sender] send_files failed to open "/usr/lib/cups/backend/cups-brf": Permission denied (13)
rsync: [sender] send_files failed to open "/usr/lib/cups/backend/implicitclass": Permission denied (13)