https://www.google.com/search?client=safari&rls=en&q=Ashopify+allow+customers+to+create+account&ie=UTF-8&oe=UTF-8

From your Shopify admin, go to Settings > Checkout and accounts. In the Customer account settings section, set up your customer account settings: To show a login link in the header of the online store and on the checkout page, select Allow customers to log in from online store and checkout.