To embed you FlexBooker booking form into a Wix site, please follow these instructions. You should use the "Embed" type of widget when creating your widget in FlexBooker.
1) Click on the "Add" button, then in the "More" catagory choose the "HTML Code" option:
2) From the element that appears, click on the "Enter Code" button:
3) From the "Share" page of the "Booking Forms" section in FlexBooker, copy the code snippet to embed:
4) Paste that into the Wix "enter code" area: