Hello.
Unfortunately, Booking Calendar does not support the upload or attachments during booking process. Sorry.
If you need that visitor upload some file during booking process, then please configure in the email template (that sending to the visitor, after visitor made the booking) some link to the “secret page” at your website, where will be exist some form for uploading files.
For uploading files, please use some other plugin. Then just insert into that “secret” page some form for ability to upload file by your visitor.
Kind Regards.
