The article is about v4, very old version.
Definitely, not helpful for the version you are talking about.
As you can see in this output, sudo still available in the latest version (13.0.0):
[root@LABBIGIP1:INOPERATIVE:Disconnected] config switchboot -l | head -n 3
Current boot image:
HD1.10 - title BIG-IP 13.0.0 Build 0.0.1645
[root@LABBIGIP1:INOPERATIVE:Disconnected] config sudo
usage: sudo [-D level] -h | -K | -k | -V
usage: sudo -v [-AknS] [-D level] [-g groupname|gid] [-p prompt] [-u user name|uid]
usage: sudo -l[l] [-AknS] [-D level] [-g groupname|gid] [-p prompt] [-U user name] [-u user name|uid] [-g groupname|gid] [command]
usage: sudo [-AbEHknPS] [-r role] [-t type] [-C fd] [-D level] [-g groupname|gid] [-p prompt] [-u user name|uid] [-g groupname|gid] [VAR=value] [-i|-s] []
usage: sudo -e [-AknS] [-r role] [-t type] [-C fd] [-D level] [-g groupname|gid] [-p prompt] [-u user name|uid] file ...
[root@LABBIGIP1:INOPERATIVE:Disconnected] config
Can you provide the output of the CLI prompt and result when you run the sudo command?
F5 uses CentOS Linux, so you can install RPM packages.
F5 does not provide RPM packages, and the recommendation is to perform the F5 software installation, and that will install all required RPM packages.