Our normal checkout process is to take customers straight to the checkout page once they have confirmed their basket (and chosen their delivery rate).
You can change this if you want to, so that instead you take the user to a login page once they have confirmed their basket. The page will look something like the example below.
The customer can either login to an existing account, create a new one, or checkout as a guest.
Changing the checkout process
To change your checkout process go to the theme settings page (which can be accessed by clicking 'themes' from the left menu and then 'theme settings').
Scroll to the 'login options' section.
The first choice is whether to take customers to the login page (described) above.
Place a tick in the 'yes' box if you want to take them to this page.
The second choice is whether to allow 'guest checkout'. Guest checkout means that users don't have to create an account/login during checkout instead they can just click the 'checkout as a guest' link (as shown in the example above).
There's not much point in ticking the 'allow guest checkout' button if you're not going to force the customer to the login page during checkout as they won't see this page otherwise.
We've written an article to talk about the advantages and disadvantages of forced login which you can read by clicking here.