To configure the merchant integration between OFBiz and eBay you have to change the following file in specialpurpose/ebay/config/eBayExport.properties
## Merchant
eBayExport.devID - obtain from https://developer.ebay.com/DevZone/account/getkey
eBayExport.appID - obtain from https://developer.ebay.com/DevZone/account/getkey
eBayExport.certID - obtain from https://developer.ebay.com/DevZone/account/getkey
eBayExport.token - obtain from https://developer.ebay.com/DevZone/account/getkey
eBayExport.restToken - obtain from https://developer.ebay.com/DevZone/account/getkey
eBayExport.compatibilityLevel - 517 (actual eBay API OFBiz is using)
eBayExport.siteID - site id (0=US, 101=Italy, ...) obtain from http://developer.ebay.com/DevZone/XML/docs/Reference/eBay/types/SiteCodeType.html
eBayExport.xmlGatewayUri - https://api.sandbox.ebay.com/ws/api.dll (sandbox environment) https://api.ebay.com/ws/api.dll (production environment)