delphitools

After further reading, I was finally able to install the 'FGX' components onto my 'Delphi 10 Seattle' IDE. In case, it might help someone else, here is what I did (keeping in mind that I did have an older version of the components previously installed on my computer):
After downloading the 'fgx_0.7.0.69.zip' file, I unzipped it into the following folder ('C:\Delphi 10 Seattle\Third-Party Tools\FGX 0.7.0.69').
  Using a regular text editor, I opened the file named 'fgx.dproj' (located in my 'C:\Delphi 10 Seattle\Third-Party Tools\FGX 0.7.0.69\Library' folder). Within this file, I replaced all occurrences of '190' with '230' as well as '210' with '230'. Then I saved the file.
  Using a regular text editor, I opened the file named 'dclfgx.dproj' (located in my 'C:\Delphi 10 Seattle\Third-Party Tools\FGX 0.7.0.69\Design' folder). Within this file, I replaced all occurrences of '210' with '230'. Then I saved the file.
  I launched 'Delphi 10 Seattle' and opened the group project named 'FGXGroup.groupproj'.
  In 'Project Manager', I verified that 'fgx230.bpl' was active in 'Debug' configuration:


  I right-mouse clicked on 'fgx230.bpl' and selected 'Options...'.
  Within the 'DCP output directory' box of the 'Delphi Compiler' option, I replaced the '$(BDSLIB)\$(PLATFORM)\$(CONFIG)' entry with 'C:\Delphi 10 Seattle\Third-Party Tools\FGX 0.7.0.69\Library\$(PLATFORM)\$(CONFIG)'. Then I copied this new entry into the 'Package output directory' and the 'Unit output directory' boxes:


  I did the same as above (#7) for the 'Release' configuration:


  Back in 'Debug' configuration, I set the 'Build control' of the 'Description' option to 'Rebuild as needed':


  Then I built and installed 'fgx230.bpl':

                 
  In 'Project Manager', I activated file 'dclfgx230.bpl' in 'Debug' configuration:


  I set the content of the 'DCP output directory', 'Package output directory' and 'Unit output directory' boxes of the 'Delphi Compiler' option to 'C:\Delphi 10 Seattle\Third-Party Tools\FGX 0.7.0.69\Library\$(PLATFORM)\$(CONFIG)'.

I also set the 'Search path' of the 'Delphi Compiler' option to 'C:\Delphi 10 Seattle\Third-Party Tools\FGX 0.7.0.69\Library':


  Then I set the 'Build control' of the 'Description' option to 'Rebuild as needed':


  Finally, I installed 'dclfgx230.bpl'.
  If everything worked properly, the 'FGX' components should now be part of your IDE.