The SysAdmin module is used to license the PBX to our licensing servers and is a requirement for all commercial modules, I haven’t personally tried to install it on a system without Fail2ban installed so I’m not sure how that would work, remember the modules are officially supported on the FreePBX Distro and PIAF version 2.0.6 and above, any thing else is not officially supported or tested. The basic SysAdmin is a free module so you should be able to give it a try.