Taking parts from opensource projects

Hi everyone. I am new to freecodecamp and have been working through the exercises to brush up on my long forgotten HTML and CSS with the intention of dedicating a full year to learning how to create my own web applications.
Coming from a commercial background in software where I ran global sales teams and strategies for going to market, I want to be able to produce my own web apps so that I can take them to market myself.
I know that the likes of Rapid7 and Tenable came from opensource projects but I would like to understand the intricacies in this.

Is it permitted for me to take code from a project that is licenced under Apache licence and incorporate this into my own web application?

What I would like to do is take the scanning engine of an open source project and wrap a new UI on it with additional features that are often requested from enterprise level customers.
The scanner I have in mind has API’s for scanning and crawling, can I just use these legally and connect my front end to this to get the desired results or would I need to completely rewrite the software?

Any help is greatly appreciated on this side of things.

If anyone requires help on the commercial aspects and taking products to market globally, please feel free to reach out.

Thanks in advance