User Defined Target Unity 2017.2

Hi all, I started using Vuforia for a few days and I am trying to understand the operation well. I have a problem with the detection of a particular image: It is an invoice (then text document). I tried first of all to upload the image in the Vuforia database but the rating was 0 out of 5, following the guidelines I managed to take it to 1 star out of 5. I can in no way change the content or colors of the image as the customer needs it as it is. So I thought I'd try with the User Defined Target (I hope it's the best way to do that) but the guides I found are with Vuforia 6.2.6 (old). I currently use Unity 2017.1 with Vuforia 6.2.10 (for the User Defined Target has undergone some modification) or I tried Unity 2017.3 with integrated Vuforia but there seems to be no option.

Now I ask you:

-Is there a way to use the image with 1 star in an optimal way? -If with the User Defined Target, where can I find some material that explains how to use it on unity 2017.2 or 2017.3 or on Vuforia 6.2.10? -Could I otherwise set reference points on the image manually?

Thanks in advance for any advice and solutions.

Manuel.