95% of humans have no attention to detail skills.
95% of humans have a 10-15 second attention span.
95% of humans can't, even if they want to, get past the first few bullet points or paragraph and a half of a document.
95% of humans are stupid as fluck.
..and
95% of humans don't want to do any work/make any effort, and expect something for nothing. They are lazy.
I wouldn't even ask them for their email. It's too hard, cause they would usually need to enter their email address TWICE and then the password TWICE then check their email to verify themselves. And this is not to mention all the Tab key presses and mouse clicks involved in this rigmarole.
Forget it. It's too hard/too much commitment.
I would just have a simple small panel (collapsible) integrated in the website (say, first panel in the left frame) which invites them to assign a 'nickname' for their 'Session' and a password.
Have an info box on the panel informing them that if they enter a password once then the system will assume they want to reconnect to an existing session, and if they enter a password twice then the system will assume they want to create a new session.
No having to click a separate button to create a new, and a different button to continue an existing, session. It's superfluous clutter.
You have to get them 'in the funnel' before requiring them to invest any real effort.
It's like fishing. You gotta get them on the hook first. And you have under 20 seconds in which to do it.
Hence I don't suggest a popup sign-on panel because it blocks their view of something underneath they might spot which might get them on the hook.
If you don't want to put a collapsible login panel in the left frame, then perhaps a left side slide out is okay in terms of not obscuring their view of something that might get a bite.
I use 'Session' above, but the nickname they choose becomes their Customer ID, thus they are really creating a new customer. But don't use the word 'Customer' at that stage because is sounds to committal. Hence I suggest calling a 'Session', what the system will treat as a Customer.
If they order something, then they will expect to attach their email, name, etc. to their 'Session Profile'. And maybe they will even want to change their Session 'Nickname' when they decide to get serious.
The above is possible (never having to leave the webpage and use the Aware login screen) if you design an application around using Session_ID().