Accept my apologies for not getting back right away Pedro. This can be accomplished through Custom function. 

Note: You can use this sample code for all modules provided you change the module names and field names as per your requirement.

Create Contacts from Custom Module :

Setup ->Automation -> Actions -> Custom functions - > Configure Custom Function -> write your own ->

1) Choose the respective module name.
2) Give custom function name and click on 'free flow scripting' 
3) Copy and paste the code below with the names modified. 

Code :

CustomModuleDetails = zoho.crm.getRecordById("CustomModule1", input.customId);
ContactMap = map();
ContactMap.put("First Name", ifnull(CustomModuleDetails.get("First Name"),""));
ContactMap.put("Last Name", ifnull(CustomModuleDetails.get("Last Name"),""));
ContactMap.put("Email", ifnull(CustomModuleDetails.get("Email"),""));
ContactMap.put("Date", ifnull(CustomModuleDetails.get("Date"),""));
ContactMap.put("Birth Date", ifnull(CustomModuleDetails.get("Birth Date"),""));
ContactMap.put("Mailing Street", ifnull(CustomModuleDetails.get("Mailing Street"),""));
ContactMap.put("Mailing City", ifnull(CustomModuleDetails.get("Mailing City"),""));
ContactMap.put("Mailing State", ifnull(CustomModuleDetails.get("Mailing State"),""));
ContactMap.put("Mailing Zip", ifnull(CustomModuleDetails.get("Mailing Zip"),""));
ContactMap.put("Phone", ifnull(CustomModuleDetails.get("Phone"),""));
ContactMap.put("SMOWNERID", ifnull(CustomModuleDetails.get("SMOWNERID"),""));
ContactMap.put("Company Name", ifnull(CustomModuleDetails.get("Company Name"),""));
ContactMap.put("Industry Type", ifnull(CustomModuleDetails.get("Industry Type"),""));
ContactCreate = zoho.crm.create("Contacts", ContactMap);

4) Click on 'edit arguments'
   a) Map fields to variables and save
5) Click on save and Associate with workflow.

Hope this helps, also you can refer to custom function for more information.