CRM users do not need direct login access to Sage 100. However, the integration does require a single dedicated Sage 100 user license for CRM to talk to Sage 100.  This Sage 100 license is used while writing from Sage CRM to 100 (insert/update) and also while adding line items.  For example, at the time of any promote process (promote customer, or promote order), the integration logs into Sage 100 using the available license --> writes to Sage 100 --> logs off of Sage 100. So that means if it takes 2-3 seconds to promote a customer from Sage CRM to Sage 100, then the license is consumed for those 2-3 seconds and a license will need to be available.  In larger installs of Sage CRM with a high volume of integration activity, our recommendation is to have 2-3 Sage 100 licensing available.