Hello Jorge,
The issue is answered, you need not do any development for the same, this can be solved through filters maintained as part of SAP CRM middle ware.
Following is the solution which you need to do
Go to tcode R3AC3 Click on object DNL_CUST_KTOKD
Click on tables and structures and ensure that you maintain the filter for both the tables, T077D, T077X as shown below.
Hit the filter setting and maintain the required account groups which needs to be downloaded to SAP CRM.
Run the initial load again in tcode r3as object DNL_CUST_KTOKD
Once you perform the above mentioned steps only the required account groups will appear in SAP CRM.
Kind Regards
Atul