UPS SurePost is a specific type of shipping service offered by UPS and must be enabled separately from a standard UPS account. Contact EasyPost at [email protected] to request SurePost be enabled and be sure to include the email address that was used to create your EasyPost account.
EasyPost will follow up with confirmation once SurePost is available to be configured as a new carrier on the EasyPost dashboard.
From there, visit your add carriers page in SKULabs and choose EasyPost in the type dropbox and follow the instructions.