Please create a Contact for the Salesforce Users that will be the Campaign owners in Salesforce.
Create a Contact lookup field in the Campaign Object and link it to Contact of the Salesforce User (for example the field API Name for Contact in the Campaign is "Contact__c").
Using the Config page you can create a where clause like below.
Filter for JOB
GW_Volunteers__Display_on_Website__c = true and GW_Volunteers__Inactive__c = false and GW_Volunteers__First_Shift__c = null and GW_Volunteers__Campaign__r.Contact__c = '$#contact_id##' order by Name, GW_Volunteers__Campaign__r.Name
Filter for today's Shifts
GW_Volunteers__Volunteer_Job__r.GW_Volunteers__Display_on_Website__c = true and GW_Volunteers__Start_Date_Time__c >= #@#st_today#-# and GW_Volunteers__Start_Date_Time__c <= #@#en_today#-# and GW_Volunteers__Volunteer_Job__r.GW_Volunteers__Inactive__c = false and GW_Volunteers__Volunteer_Job__r.GW_Volunteers__Campaign__r.Contact__c = '$#contact_id##' order by GW_Volunteers__Start_Date_Time__c asc
Filter for Volunteers today
(( GW_Volunteers__Shift_Start_Date_Time__c >= #@#st_today#-# and GW_Volunteers__Shift_Start_Date_Time__c < #@#en_today#-# ) or ( GW_Volunteers__Planned_Start_Date_Time__c >= #@#st_today#-# and GW_Volunteers__Planned_Start_Date_Time__c < #@#en_today#-# )) and (GW_Volunteers__Status__c = 'Confirmed' or GW_Volunteers__Status__c = 'Prospect' or GW_Volunteers__Status__c = 'Web Sign Up') and GW_Volunteers__Volunteer_Job__r.GW_Volunteers__Campaign__r.Contact__c = '$#contact_id##'