First, I gave a look into the Size of Wikipedia article.
This is an estimation of the size of what English Wikipedia would be if printed in early 2020, without the images:
This is 13 full bookcases and a 14th bookcase being built. To account for all the future growth and also add the images, let's consider it 30 bookcases. This fits into a library room (and let's call it a standard library room).
This is the size of the English Wikipedia in comparison to its other languages versions:
So, let's say that the English version is 10% of it. To account for future growth of articles in other languages to the size of eventually competing with the English one, let's give 5% to English.
This means that everything on Wikipedia would fit 20 standard rooms in a library.
Let's consider that all the Wikipedia contains 10% of the useful knowledge. The other 90% comes from articles, books, magazines, GitHub, YouTube videos transcribed as comics, other stuff. This gives 200 standard rooms full of books. That is a huge library occupying the size of a large building, but far from impossible. Also, if needed, splitting it up into smaller buildings is feasible.
Now, deploy a thousand of such libraries around the world. Most of them should be easily accessible, just walk into the building, start entering rooms, open bookcases and get the books. To ensure survival from thousands of years of earthquakes, fires, tornados, hurricanes, floods, molds, wars, dust, storms, looters, vandals, etc, put at least a few hundred of those libraries being contained into sealed vaults filled with an argon atmosphere.
The sealed vaults should feature some large stones in the front of their doors. Those stones should contain the instructions of how to safely open them and access their content. Those instructions are carved down into the stones and written in several languages. But opening the vaults should require a large group of determined people, should not be too easy and should not be harmless if done incorrectly. This serves to deter random looters and vandals.
Those sealed vaults could be underground caves or mines or pyramids built with this sole purpose in desert areas, glaciers or mountains far from geologic failures and significantly higher than the sea level. They also contain empty void areas below them with a drain to elsewhere and also hollows in the walls in order to ensure that any infiltrating water goes down and drains elsewhere and don't damage nor reach the chamber.
To make at least one of the languages understandable for people speaking something not familiar to any of them, put millions of language books in the first room of the library or perhaps into thousands of mini-libraries. Those language books starts with things like this:
Further, the book pages might not be made of ordinary paper. Should be made of something resistant to corrosion, abrasion, water, heat, fire, cold, shock, wearing, wrinkling, tearing, crumpling, molds, ants, termites and goats but also be nearly worthless for anything other than their intended use and also should be something cheap and abundant. Maybe thickened aluminum foils will do. Maybe plasticized canvas treated with a fire-retardant and impermeable varnish. Of course, they are just resistant to accidents, misuse and to the elements of nature, but this is still far from being indestructible for someone intending to destroy them. The thickening of the paper will make it use much more space, but even if you make each library occupy the quadruple of the space that one full of common papery books would occupy is still ok (so, each library have 800 standard rooms). To further discourage its usage by looters, give a huge stock (the equivalents of further 1200 rooms) of "blank pages" in the entrance of those libraries, so they would prefer to loot those, but put a clear sign telling apart what is the real treasure and what is not.
In the end, each of those libraries would be the size of a stadium, a shopping center or a skyscraper, but most of that structure would be buried deep underground for safety.
If you want to reduce size, you could also put all those stuff into high density SDD storage, so each library would easily fit a very large server and add an annex in the form of paper-library telling how to build the tech needed to read them. And then, deploy tens of thousands of those scattered in the globe.