Download the latest MCreator version for Linux and extract the tar.gz archive to the desired location of your choice.
NOTE: You can install MCreator anywhere, but make sure that there are only numbers, English alphabet characters, characters .,-_ and whitespaces in the name of the file path. Other characters from other languages might cause unpredictable errors and problems so avoid using them!
Go into MCreator folder you just extracted and open in in the terminal.
Once you open the terminal in the folder of MCreator, run the following command in it:
The command shoud look like this in the terminal:
Once you run this command, MCreator will setup itself and you can start using it. Once you launch MCreator with this command, it will make a launcher icon in the installation directory and on the desktop. You can use these icons to launch MCreator without opening the terminal each time. Keep in mind that if you move the installation directory, you need to do Step 2 again.
If you are looking for installation instructions for older releases, check MCreator's Wiki for the legacy installation procedure.