Custom order fields are needed in SalesForce for Extensiv Integration Manager to upload tracking info. 

Step-by-step guide

1. Go to your SalesForce Dashboard, then click Setup at the top-right corner. 
2. Type order in the Quick Find/Search box. 
3. Go to Customize → Orders→ Fields. 
4. Scroll down to the bottom of page, and click New under the Order Custom Fields & Relationship section.
5. Select data type Text, and hit Next.
6. Fill in custom field info: 
   • Field Label: Tracking
   • Length: 128
   • Field Name: Tracking
   • Required, Unique, External ID fields are not checked. 
7. Click Next to configure Visible and Read-Only permission. Then, keep clicking Next and Save to finish setting up custom fields.
8.  Repeat steps 4 to 7 with following custom field info: 
   
   • Field Label: Carrier
   • Length: 128
   • Field Name: Carrier
   • Required, Unique, External ID fields are not checked.
9. Copy custom fields API Names and paste them to Integration Manager SalesForce Cart Setup page.
   

https://static.helpjuice.com/helpjuice_production/uploads/upload/image/12985/direct/Sample_SF_Data_Mapping.xlsx

https://static.helpjuice.com/helpjuice_production/uploads/upload/image/12985/direct/SalesForce_Data_Mapping.xlsx