Hey there, this is going to be a zombie reply, but I'll share it because I have some details.
I've been trying for a while now to get a port of racadm working in FreeBSD (and it may finally happen). That bug is here:
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=201799, and you can see that lots of people ask the same questions again and again. Anyway, if it happens, there's a few catches:
1) It will require the linux subsystem and
2) You'll have to build the port yourself (no pkg, for Dell licensing reasons)
3) If you want to use it to talk to your local machine, you'll have to configure the internal USB nic that the idrac exposes, and talk to it that way.
You can also do this without racadm, and just ssh, internally, to the idrac, where there's a slightly more limited version of racadm running ("embedded racadm"). You can even add an ssh pubkey to your idrac and your FreeBSD OS so you can do this in a scripted fashion. Or you can speak snmp, internally or externally, to the idrac.
Under Linux, it *used to be* that racadm spoke some weird undocumented form of ipmi, but nowadays, it just connects over https, internally. (ipmi, I think, is still used to do things like reset the card and configure the ip address).
The FAQ I've written (which I'll update if it becomes a port) is at:
SysAdmin Combat Story #29, collect them all.
gushi.medium.com
One more note: I have found a few cases of some Supermicro machines needing extra licenses for things, especially for mounting remote media, so they're not perfect here.