It sounds like you are trying to pass the name and email address from a Keap form to your ScheduleOnce booking page so contacts do not need to fill this information out multiple times.
To do this, you will need to pass the contact’s name and email through the URL using the URL parameters specified by ScheduleOnce, combined with the merge code values unique to Keap.
For example, let’s pretend your ScheduleOnce booking page URL is https://go.oncehub.com/PageLink.
If you wish to pass the name and email address to this booking page from Keap, you would need to create a link that looks like this: https://go.oncehub.com/PageLink?name=~Contact.FirstName~&email=~Contact.Email~, where ‘name’ and ‘email’ are the parameters specified by ScheduleOnce to populate those field values on the ScheduleOnce booking page.
In order for Keap to properly update the ~Contact.FirstName~ and ~Contact.Email~ merge code values, you would need to add a link to your Keap webform’s Thank-you page that says something to the effect of ‘Click Here to Confirm a Meeting Time’, and links to your URL with the merge code values: https://go.oncehub.com/PageLink?name=~Contact.FirstName~&email=~Contact.Email~:
The ‘Web address option currently won’t work since ScheduleOnce is looking for specific parameters (for example, ‘name’), instead of the default values sent by Keap:
The above information can be used to auto-populate both the ‘Name’ and ‘Email’ fields on your booking form. If these are the only fields you need completed on your booking page (besides choosing a booking date/time), you can also consider adding the &skip=1 parameter to your URL above to avoid contacts having to confirm their information in ScheduleOnce since they just provided it on the form within Keap. If you choose to do this, your final URL would be https://go.oncehub.com/PageLink?name=~Contact.FirstName~&email=~Contact.Email~&skip=1
This information and more can be found on Schedule Once’s support article, here: URL parameters syntax and processing rules | OnceHub