Mac book pro 2018 can't be connected?

I have a problem today I bought such a cable with a USB c port for my Mac book and a normal USB port so that I can transfer things from my Mac to other laptops or computers. I first tested it on my mobile phone and it said "Access to this device is not possible. Connected device requires external power supply, unfortunately I don't know what that means. What did I do wrong? Can someone please help me to transfer my data?" can I need it in 2 weeks for the. LG salome

Your opinion lol

Your problem. Lol