Hi @Ap_Sundaram,
As your requirement is to automate the documents processing task and these documents can be photo copies as well, I would suggest usage of Document Understanding framework of UiPath as this framework has all what you need to fulfill your requirement.
Document Understanding is the ability to extract and interpret information and meaning from a wide range of document types (e.g., structured, unstructured), storage formats (e.g., images, PDFs, text), and objects (e.g., handwriting, stamps, logos).
And for this, framework is already available for use, you just need to customize it per your requirement and Ta-Da!
Follow the link below to know more about framework:
To know more around the functionality of UiPath Document Understanding, please refer below links:
Also, to learn in detail, there is also a course available on UiPath Academy for document understanding, its really helpful to gain insights on the process:
https://academy.uipath.com/learningpath/uipath-document-understanding-overview-3
Another course below on learning orchestration process(this can be taken up after document understanding lesson to deep dive into different ways of orchestrating the workflow):
Regarding your requirement to inform the candidate about missing detail can be handled in multiple ways. Herein also, in case you need to get the missing details from the candidate, you can make use of another UiPath product - Action Center. Using Action Center, you can be able to submit and assign the task to the user (also attaching copy of the form) requesting the missing details.
Hope this info helps 
Regards
Sonali