You can’t see them because this is that game.
Warcraft III Reforged is in fact just a patch to the original game. Thus, you can’t buy that because it will just update to this.
When they came out with Diablo II Resurrected, they figured out that was dumb and made it a separate game (even though it is mostly a new graphics engine slapped over the original game engine). But that happened too late for War3.
If you want to buy Warcraft III today this is the only option, even if you don’t want the Reforged graphics. You just select classic mode and that’s all there is to it.
They will need their own battle.net account and their own copy of the game. You can’t install the game on a bunch of PCs like in the olden days. That’s just how games work today. Not just W3R, but almost all PC games that aren’t freeware or indie.
If you dig around on the internet, you can find the original installers. But you can not go online with the original game because it will update to the Reforged version. You can however, play LAN with that as long as you don’t mind it being an unpatched out of date version.
Also if you want to just be like “this is what the games I played were like when I was younger, my nephew,” Buy reforged on two accounts, play for a while, then refund them. They are still no-questions-asked refunding this game.
Originally one of the reasons they did remasters of the classic games was so they could move them to the new battle.net network. This is one of the reasons they made all War3 clients patch to the Reforged version. But after the backlash from that, with Diablo II they left the original version online. So they still can’t free themselves from their old battle.net network entirely.
If you have the RoC key on your account, if you go here > https://account.battle.net/games#classic-game-accounts you can do a manual install and then it should work.