I read this online. Figured it may be for the steam version. Is this true? Thanks.

Yes. It is true for all versions of the game. OK, a tiny primer, here...;) Achievements are add-ons for games--they are like "afterthoughts", in a way, because they are only created after the game is completed and finalized. All they are is little metrics for various things that the developers allow you to tally--things which often are bizarre and have nothing whatever to do with the game itself! It's all to enable a sort of "my achievements are bigger/better than your achievements" kind of "gentlemen's competition, ladies included" as you play the game--you can compare achievements with your friends or even set out to do them yourself, if you want. Fun for the whole family.

You know, stuff like the "I killed everything moving in the game and then I killed myself" achievement. Dig? Or the "I ate all the dogs in the game" achievement, or the "I swam on the backs of four sharks before being eaten by one" achievement, or the "I sat in a pool of blood for 88 hours of game time" achievement, etc. There are all kinds of fun achievements like this that you can spend hour after hour enjoying and repeating, constantly, even if you never actually play the game at all! That's the sheer beauty and joy of achievements! Know what I mean, Imojean? Dig? My favorite achievement is the "If this guy makes one more stupid crack about achievements I will vomit in my lap" achievement. Cool, Daddy-o, eh?

But if people running mods were allowed to compile these super-interesting, famously intellectual achievements, too--it wouldn't be fair to the hardcore gaming element out there, would it? I should say, "the hardcore achievement lovers out there," would it? Heck, no, dude! Suppose you are running the "Heightened watermelon-blast explosive radius" mod. Would it then be fair to get the "Explode hugely each time I eat a watermelon" achievement? I don't *think* so,,,,noooo-o-o-o-o-! No fair, and no way, Jose'!

With all of this firmly in mind, the developers of the masterpiece (no joke, that!) OS 2 RPG are insisting on a *level playing field* for those brave, pioneering souls who refuse to buy any game unless it offers it's own rack of meaningful achievements! Dig? 'Nuff said! 'Njoy...;)

Simple fact is, the vast majority of mod users, have never cared about trashy add on achievements, and never will.
You can't expect ac hievements when mods can easily be used to bypass all the obstacles to getting them.

If you want achievements, you don't use mods.
If you wan't mods, you can't expect to be awarded Vanilla based achievements.
You can have two profiles, one for Vanilla, and one for modded, and have both.

The fact mods disable them is a bonus feature as far as I'm concerned, and I wish I could turn them off that easily in every damn game.

I really agree with this...;) Steam started that nonsense. But I've been surprised at the people who think it's actually a part of the game they're playing--I was just having a bit of fun above and throwing off on the whole concept. Maybe, for some people, in a replay, it's something else to do--but I agree that it has little to do with the game and if the mods are quality mods it's usually much more fun to use them.

Having said all that, now a mod exists to re-enable Achievbenents, it was only uploaded an hour ago

It's replacing Game's Bin folder bink2w64.dll file, and strangly Credits Fallout 4 Script Extender (F4SE) team for F4SE.

Achievements by Kassent
[spoiler]
[Introduction]
Re-enable achievements while using mods.

[Requirements]
Divinity: Original Sin 2 V3.0.146.969(Latest version) or above(GOG or Steam version).I only tested it with latest GOG version,it should work with latest Steam version too because the binary codes I patched is same.This mod is designed to be version indepedent,so as long as the patched function sigs don't get broken,it should work with upcoming game update,if it doesn't work in future,I'll update it.

[Installation]
Extract archives to the folder where EoCApp.exe is located, overwrite or rename bink2w64.dll if exists.For more details view the pictures.

[Uninstallation]
Delete bink2w64.dll and NativeMods folder,rename bink2w64_original.dll to bink2w64.dll.

[Credits]
reg2K for signature scan algorithm.
Fallout 4 Script Extender (F4SE) team for F4SE.

[SourceCode]
Source code for someone interested in(Github).
[/spoiler]

Yes, I heard about that later, too...;) I also noted that for changes, mods used to remain enabled if you installed a non-.pak file mod, like texture mods, etc. But I guess this new mod covers the bases...;) Still don't think they are germane to the game, but I have to concede that some people really like achievements, apparently.