I can do this in Cinema 4D but it will take a lot of time, looking for an alternative software that creates 3D looks like a 2D scene in real quick.
As @AAGD suggested, this is a hand-drawn raster image. It wasn't made in any 3D software.
You can create the same in nearly any type of raster image software with a brush/pencil tool that supports drawing without any softening, for that aliased edge look, typically referred to as pixel art. PhotoShop, the most well known, can do this with its pencil tool.
These days there's a lot of dedicated software for drawing pixel art. There's actually so many that I'd suggest Googling for them rather than me listing any here. They provide a reduced and refined set of tools dedictated to pixel drawing and typically show their strengths with animation tools specifically geared towards pixel art. Ultimately, a good ability to illustrate is fundamental to using any. Whichever you use is just personal preference.
As with lots of illustrations and paintings, the artist used their understanding of what an isometric 3d view would look like at a chosen angle - intuition and observation, basically - rather than any sort of 3d tools.
In terms of the easiest approach: once the artist had the basics drawn in one area, they were able to copy lots of the scene into other areas. Besides the obvious duplication of pixels for various desks, chairs and pillars, a lot of the walls are repeated and these would have been copied too.
I'll also add that a lot of people aren't aware of using the pencil tool in PhotoShop in conjunction with the shift key. This is pretty essential for pixel art. With the shift key held, you can force straight lines at 90 degree angles. Secondly, if you click one point, hold shift and click another point, PhotoShop automatically draws a straight pixel line between both points, at any angle. Once you have base lines set up at the angles you'll be using throughout the image, you can copy them elsewhere to extend and add new lines. It's a very rapid way of sketching out a scene while retaining the same angle for lines.
There's a tool out there called MagicaVoxel which is open-source and free, allowing voxel based world and image building which I think would make this kind of image really fast to do.
I've played with it a bit (I'm a 3D generalist) and it's low-barrier and fun enough that I think a hobbyist could learn it quickly.