1. Create a directory where you would like access ECLiPSe from.
   (e.g., /Applications/eclipse).

2. Navigate to https://eclipseclp.org/Distribution/CurrentRelease/6.1_164%20x86_64_macosx%20Intel-64bit-MacOS/ to download the binary of release 6 of  ECLiPSe Prolog.

3. Right click on each of the file links and choose the save link as option
and save it to your eclipse directory. If you have the wget command installed, open terminal, navigate to the directory using cd (e.g., cd /Applications/eclipse) 
and run the following command:
wget -r -R "index*" --no-parent -nd -nH https://eclipseclp.org/Distribution/CurrentRelease/6.1_164%20x86_64_macosx%20Intel-64bit-MacOS/.

4. Open terminal and change directory to the eclipse directory you created in step 1, e.g., cd /Applications/eclipse. Type the following command in terminal: chmod u+x UNPACK

5. Run unpack from terminal using ./UNPACK

6. Run RUNME from terminal using ./RUNME

7. Press the Enter/Return key to accept the settings. In the case of the prompt to specify the Java directory, you may skip it, or provide your directory where Java is installed on your system.

8. Navigate to bin/x86_64_macosx in Finder and launch the xtkeclipse executable. Now it is possible that you may get an error when running  xtkeclipse  if you are on MacOSX Catalina or later. If that is the case, try the following. Navigate to https://www.xquartz.org/,  download XQuartz dmg file and run the installer. You may be required logout and login after the install process. Try running the xtkeclipse executable to see if that fixed the issue.