Seamless.AI has native integration with Salesforce, however, SF Professional and SF Essentials require a different set of steps to integrate with Seamless.AI.
Salesforce Professional and Salesforce Essentials have limitations on their API access, which is required to directly integrate Seamless.AI + Salesforce.
SF Professional - This requires an additional API Package to be purchased. For Salesforce Professional users, please contact your account manager to activate the API package so you can integrate directly with Seamless.AI. You can find more information on this here.
SF Essentials - Salesforce Essentials does not offer an API package, however, Seamless.AI directly integrates with Zapier. Zapier offers integration with SF Essentials so you can integrate directly with Zapier and have this information port directly into Salesforce. You can find more information on this here.
You can purchase the additional API package for your SF account, or you can upgrade to SF Enterprise and this API integration will be included in that package.
You can find details on how to add API packages to lower level Salesforce Editions: