I've been presented with the opportunity to build a pretty complex website (complex for my experience). I'll be honest, I'm new at this. Not brand new, I've built several functional, secure websites. But my first instinct was that this project was over my head. The individual owns an apartment complex and needs a website for his residents to login and view specific details about only their units, pay their bill/fees, etc.
Is this something that is reasonable/possible to do with WordPress?
Let's phrase question like this — would using WordPress for the project help your chances more than harm your chances? Note that it's not either, there will be both help and harm aspects to such decision.
On the help side — WP has low initial learning curve. It is easy to install, easy to do basic (theme template level) customization and development, and has very very rich extensions ecosystem to supplement core functionality.
On the harm side — advanced development starts to quickly hinge on making very careful considerations about how project's data aligns (if it does at all) to WP concepts and functionality. This skill doesn't come easily (mildly put) and you can't pick it up quickly.
It's not about if WordPress can do it. WordPress can do anything.
It's about if you can do it with WordPress.
My educated guess would be that you have doubts if you can do it at all and it doesn't sound like a project very aligned with basic WordPress development. So I would guess the harm side wins in this one.
