https://stackoverflow.com/questions/58840411/innosetup-choose-custom-files-to-install

SelectCustomMacro.iss

; DEMO innosetup script to let user select macros to install

#define MyAppName "Choose custom files for install"
#define MyAppVersion "1.0"
#define MyAppPublisher "CitizenInsane"
#define MyAppURL "https://stackoverflow.com/questions/58840411/innosetup-choose-custom-files-to-install"

[Setup]
; NOTE: The value of AppId uniquely identifies this application.
; Do not use the same AppId value in installers for other applications.
; (To generate a new GUID, click Tools | Generate GUID inside the IDE.)
AppId={{85C7F0EE-A37A-4650-B360-75628C8ACA2C}
AppName={#MyAppName}
AppVersion={#MyAppVersion}
;AppVerName={#MyAppName} {#MyAppVersion}
AppPublisher={#MyAppPublisher}
AppPublisherURL={#MyAppURL}
AppSupportURL={#MyAppURL}
AppUpdatesURL={#MyAppURL}
DefaultDirName={pf}\{#MyAppName}
DisableDirPage=yes
DefaultGroupName={#MyAppName}
DisableProgramGroupPage=yes
OutputDir=deploy
OutputBaseFilename=setup
Compression=lzma
SolidCompression=yes

[Languages]
Name: "english"; MessagesFile: "compiler:Default.isl"

[Dirs]
Name: {app}\macros

[Files]
Source: ".\macros\*.txt"; DestDir: "{app}\macros"; Flags: ignoreversion; AfterInstall: AfterInstallEachMacro;

[Code]
{* Global variables*}
var
  GMacrosTotalCount : Integer;
  GMacrosFullFilenames: TStringList;
  GMacrosSelectectionPage : TInputOptionWizardPage;
  
{* On setup wizard initializing *}
procedure InitializeWizard();
begin

  {* Init *}
  GMacrosTotalCount := 0;
  GMacrosFullFilenames := TStringList.Create();
  GMacrosSelectectionPage := CreateInputOptionPage(wpInstalling, 'Macros', '', 'Select macros to install', false, true);

end;

{* On each new macro added *}
procedure AfterInstallEachMacro();
var 
 filename : String; 
begin
 
  filename := CurrentFileName;
  filename := ExpandConstant(filename);
  GMacrosFullFilenames.Add(filename);

  filename := ExtractFileName(filename);  
  GMacrosSelectectionPage.Add(filename);
  GMacrosSelectectionPage.Values[GMacrosTotalCount] := True;
  GMacrosTotalCount := GMacrosTotalCount + 1;

end;

{* On clicking next button *}
function NextButtonClick(CurPageID: Integer): Boolean;
  var index: Integer;
begin
	Result := true; 

  {* When leaving page for macro selection *}
  if (CurPageID = GMacrosSelectectionPage.ID) then begin
    
    {* Delete macros the user do not want *}
    for index := 0 to (GMacrosTotalCount - 1) do 
    begin
      if (not(GMacrosSelectectionPage.Values[index])) then begin
          DeleteFile(GMacrosFullFilenames[index]);
      end;
    end;

  end;

end;