First of all, add your signature, describing your software versions and hardware configuration! Writing your own name would be nice too, as nobody likes to give advice to strangers. This is the proper etiquette in the forum and it will very much help us help you! And, please, don't cross-post!
To your question - the method you describe sounds strange! Do a search in the forum and and you'll find many discussions on the subject!
Of course you'll have to "recolour" your model in Max - you can't expect AC to have the same mapping capabilities as Max does! 😉
Groups can't be exported as groups! Walls will be "grouped" in Max if they have the same material.