You are setting up a brand new Magento installation for a merchant who is migrating from Magento 1 to Magento 2. Keeping in mind upgradability and the need to customiz.
A. Create a new Magento instance using composer create-project
B. Clone the magento/magento2 GitHub repository
C. Run php bin/magento setup:migrate <path-to-m1-installation> <new-version> command
D. Create a new Magento instance by using the bin/magento install command