The Nosto Magento 2 MSI module requires at least PHP version >= 7.1.0 and Nosto's Magento 2 module >= 4.0.0
Installing the extension
Currently the only way of installing the extension is via Composer. If you don't have composer installed yet you can get it by following these instructions. It's recommended to install composer globally. You will also need public key and private key from Magento Marketplace or Magento Connect in order to install packages to Magento 2 via Composer. Please follow these instructions to get public key and private key http://devdocs.magento.com/guides/v2.2/install-gde/prereq/connect-auth.html. Once you have composer installed you can install Nosto extension (nosto/module-nosto-msi).