Just had a brief look at the .dae file, but it's not ok at all!
It needs some work to be printable.
-planes not intersected.
-parts not attached to floor.
-windows not intersected.
Some points to think about;
What size do you want the print to be?
If you make it to small, some details won't show!
Its possible to create an outside shell, and keep the exterior appearance.
It's important to know what size you want it!
Then it's easier to save as much material as possible.
Walls need to be a certain minimum thickness to be printable.
But if you upscale it later, walls will be thicker and more expensive.
So the size is very important.
Looking at the whole model, I would be able to make a printable version, no problem!
Let me know if you still need help
Kind regards,
Alex