Command sequence results in "jarfile not found"

Hello. I have never asked a question on here before and perhaps this is the wrong place, but my niece is attempting to set up a minecraft server for her and her friends to play on and can't figure it out. Perhaps someone on here can help us. To my understanding, she has a command set up to run a jar file when the command is opened, and despite being in the same folder as said file, opening the command results in the Terminal saying "Error: Unable to access jarfile {server.jar}." We have both searched for solutions on the internet but they seemed catered towards PC users, so I decided someone in the apple community may have a better answer. Does anyone have any idea why the command cannot access this file? It is in the same folder as the command, but this error message pops up every time. Her mother is not the most technologically adept and I do not know how to code, so any help is appreciated.

Thank you all and have a lovely day!