Hi Michael,
Thanks for reaching out! Once you’ve created the tickets on the event, if you go through the checkout process to enter the information for the attendees who have already paid, then the tickets will be created and emailed out to the attendees automatically, and attendees will be added to the list for that event, allowing you to check them in normally on event day. You could also go into WooCommerce and create the WooCommerce order for the tickets manually.
You might give this solution from another user a try (importing via CSV), but I would recommend testing this out in a staging environment first before doing it on your live site, just to make sure it’s working the way it’s intended to.
Let me know if you have any questions!
Thanks,
Jennifer