I don’t see a specific mention of lube for the ratchet setup in the manual.
From the pic, it looks like a fairly typical pawl and ratchet ring design, which means something like the lubes from Shimano, DT or others meant for similar systems could be appropriate. As mentioned, you can add more lube if you suspect it is “low” for any reason. But take great care if you do, because excessive lube (or the wrong kind) can lead to poor engagement that can have very bad consequences.