Hi infomax_accountancy
There are some document that only require Signature and user do not want to place any other fields on the document so they directly send the document Out for Signature after uploading it without placing the fields on the document. In this case Adobe Sign adds a Signature block at the end of the document for the Signer automatically.
This is one of the feature of Adobe Sign.
However if you need to place fields on the document according to your requirements you will have to check-mark "Review & Add Signature" checkbox.
Feel free to reach us back if you have any query or concern.
Regards,
Aadesh