.max is not a model format, it is the native scenefile extension of 3DS MAX scenes.
So there isn't going to be a converter; but there are many advantages for someone using 3ds max to have the actual scenefile vs. just the models. All the modifier histories, lighting and GI settings, rigging, etc.

If you are desperate, you could download the 30 day free trial of 3ds max. It is a fully functional trial. You would have 30 days to open those files in the trial and export the meshes as .obj or whatever other format you want; but just 30 days. Then you have to pay to keep it working.
Maybe stock up on a bunch of .max files you were looking at first, it's a one time free deal...

Friends don't let friends use booleans.