I think something to consider is the sheer timescale that evolving civilization implies, evolution takes a very long time, and as far as we know nothing else on earth quite is as smart as humans. That means that another species on earth developing civilization implies one of three things:

That we will have been interacting in some form with their ancestors as they evolve intelligence for a very long time, and so their civilization will have evolved with and probably around ours, rather than completely separately, meaning that they probably won’t be a separate civilization so much as we’d have a shared one, or at least a loosely connected one. (Like if over the next several thousand years, some octopus was to slowly get smarter and eventually evolve to civilization, they’d do so in an ocean littered with human artifacts and shaped by human activity, and they might even need some of this stuff in some way, like maybe they develop metalworking by shaping bits of metal in shipwrecks and garbage rather than extracting it from rocks for example.)

That they already were intelligent in a way similar to humans, with language and other such things needed to develop civilization, without us knowing, but simply had not invented it yet (like humans were until around 10000 years or so ago, most of our history as a species). In this case, I don’t think just leaving them to their own devices without contact is a great idea, because they’ll probably have an extremely bad view of humans (we don’t tend to treat wild animals all that well, and especially the more intelligent ones, which we have often hunted for food or to remove competition, and they’re probably going to have a whole lot of stories and oral history about us as a result.) Since they haven’t been able to really do much in retaliation (to the point we didn’t even recognize them trying), they’ll probably think of us less as just rivals and more like unstoppable monsters to be avoided at all costs. This kind of view is basically setting us up for conflict with them later on, and will take a lot of work to address given how ingrained it probably is with their culture, so both communication and helping them out with early civilization problems that we’ve already solved is probably a good idea for peaceful relations later.

Finally, the third possibly is that they are able to suddenly become intelligent and develop civilization because we made them that way, ie, they’re either AIs of some sort, or an intelligent species we engineered, or an existing species like dolphins or such who’s intelligence we have artificially enhanced (in science fiction this is often called uplifting). In this case, their civilization is intrinsically linked with ours from the start, and if they happen to need some of our technology to exist (ie, like machines need manufacturing equipment to make more of themselves, or maybe an artificially enhanced creature needs some kind of drug to get the intelligence enhancing effect or something) then making their own civilization without help from ours in at least giving them that tech isn’t even possible. It’s possible they might still want to go out and found their own government or something, but such a thing is less like a wholely separate civilization and more like just a new country, at least at first, and so probably should be treated as such.