Did you activate RAD Studio 10.2.x option during installation? 10.2.x compiled units and packages should be installed under \Units\ERS XE102\Win32 sub-folder.
What version of TsiLang Components Suite do you try to install? Support for 10.2.x was introduced in 7.5.6. Earlier versions don't support 10.2 version of IDE.
In case you use 7.5.6 or later just select RAD Studio 10.2.x option it includes C++Builder 10.2 support.