Clone the repository at app/code/Aureatelabs/StockAlert location.
$ git clone https://github.com/aureatelabs/magento2-vsf-product-stock-alert.git app/code/Aureatelabs/StockAlert/ Enable extension and to make sure that the enabled extension is properly registered, run 'setup:upgrade'.
$ php bin/magento module:enable Aureatelabs_StockAlert
$ php bin/magento setup:upgrade