First - you need to install B2B extension for Magento 2.2 EE Separately after installing your magento 2.2 EE.
Below is the steps to install the B2B extensions :
Change to your Magento installation directory and enter the following command to update your composer.json file and install the Magento Commerce for B2B extension:
composer require magento/extension-b2b
When prompted, enter your authentication keys. Your public key is your username; your private key is your password.
Run the following commands after Composer finishes updating modules:
Here is the reference link for B2B installation
After successfully installation of B2B extension - **you need to enable it from
store -> configuration -> general -> B2B features**
Note : Make sure you add your EE user key and password then and then you will able to install this extensions..