Hi Vikash, We currently have a document linking module which is compatible with Alfresco 5.1. If you head to https://www.parashift.com.au/document-linking you can purchase the module which is currently on sale for $99USD (1 day left). I see that you have included the link as one of your options in your question. Once you purchase the product you will receive clear instructions on how to install the module and if you have any questions after that we are more than happy to help if you email: contact@parashift.com.au