Is there an guide on how to do it ? Because i have no access to mac computer and i found some tips in other threads but not an actual step by step guide. Could you help? Right now i have dmg file called "macOS Catalina 10.15.6 (19G73)" which is 8gb. I used transmac but it seems like usb is not even uefi bootable.
You want to do this before creating the bootable media because there's a good chance you format the drive with a Windows machine. If this is the case, then you are probably using an MBR partition, and the USB drive needs a GPT partition to work on a Mac.
Welcome to Apple. I heard Steve Jobs once wanted to run his stuff on dell's but he charged Michael dell like 5k and only one year of updates. Michael told him to fly a kite