UI/UX portfolio — using a pre-made elements/toolkits?

this may be a stupid question but please understand I am a 1st year student who just got on a track to be a UI/UX designer. I am trying to work on my first prototyping project to be featured on my portfolio and I have a question. Do I have to create all of the graphical elements on my own, or can I use a pre-made elements from a UI toolkit/icons someone published for free? Will companies only look at the rationale behind arrangement and composition of these elements, or will they think I am an incompetent designer for using a toolkit?thanks in advance.