You can let the user submit the quote without filling out the checkout form.
To enable it, go to Catalog Settings > Quote Cart and set the ‘Remember fields by’ option to ‘User Account’ and save the settings.
After that, check the Enable Fast Checkout checkbox and save the settings:
Once checked, the cart screen will include the fast checkout button:
If you have the quote payments enabled, the Continue button will show up only if payment is possible.
Once you click the fast checkout button, the submit box will show up:
The top of the button contains the login information (or login box if the user is not logged in).
Once the Continue button is clicked, the quote is submitted, and the user is redirected to the thank you screen.
The fast checkout button label and fast checkout information are fully customizable in Catalog Settings > Quote Cart:
Disable fast checkout guest registration
To disable guest checkout for fast checkout, go to Catalog Settings > Quote Cart and check the Disable Guest Fast Checkout checkbox.
This way, the fast checkout will require the user to log in.