This is to be used with the Mecabricks Minifigure pack. It basically automatically detects and replaces the elements with the high resolution versions that you have available locally.

Modifiers do not play very well with the instancing system which is in place to drastically cut render time and memory usage.
Subdividing is an option of the online render mode so it is definitely possible.

I have already bought the high rez model... so I can do this? are there only high rez packs for minifig parts or is there some for weapons and other bricks?

Yes of course you can 😉
This is currently the only but there maybe be others in the future.
Download the latest version of the minifigure file (2.0.0). Inside the zip archive you will find a folder called "Blender Addon Pack". This is the directory you shall select in the Mecabricks add-on preferences. See step 4 of the install PDF found in the Advanced add-on package.

Hello there,
I am seeking a method for exporting/importing the models with a higher resolution for the polygons. Is there any way of doing so?
best
-C

Not really. The online mode includes a special function to process the meshes in order to subdivide them better than just applying a subdivision modifier. The advanced add-on supports packs to replace "low-ish resolution"parts from the zmbx file by a local custom version of the mesh and functional textures textures (mold lines, etc.) that can be high resolution. Only the minifigure pack is available on the shop currently but nothing prevents you from making your own.

Ah, I see.
Thanks for the reply. I have managed to smoothen out the simple round things, just with complex shapes it won't work.
If my knowledge would go that deep. ha.
Best
-C