Common technical requirements for CRMs

Hi everyone I'm new to the sub. I'm no expert in CRMs at all, so bear with me if I not using some term correctly.

I have a personal project in which I want to implement a CRM application for a real estate agency that should work in tandem with the customer's (real estate owner) website. It's easy to find resources and readings about the theoretical stuff of CRMs. What happens is that I find myself completely lost on the common technical requirements for this industry and I also don't know "what and how" to search for it. In general (no only for real estate agencies), aside from getting a good understanding of each individual business and client requirements, is there a basic set of features that a solution should have? Also I would appreciate any books recommendation on anything close to this topic or any other type of info.

Thanks in advance.