can we use it?

no

What do you mean with a cracked server? A normal server jar which accepts cracked accounts? That is allowed if it does not modify the game, and if the cracked launcher you use also does not modify the game (TLauncher for example is explicitly banned)

ok,thank you, just asking

"A normal server jar which accepts cracked accounts?"

That would typically be alright, but connecting with a cracked account is probably not. Correct me if I'm wrong.

Connecting with a cracked account is fine by SRC rules (I verified this information with multiple mods and verifiers), but it breaks Mojang’s TOS and is therefore against the piracy law. Look at SkyRota’s comment on the issue on the javacord.