Current implementation of MONAILabel tool uses cpp-httplib as its core library for making REST api calls. (D875)
In order to enable httplib to call https based URLs, SSL support should be activated.
This should be ideally done via simply declaring a preprocessor directive #define CPPHTTPLIB_OPENSSL_SUPPORT just before #include <httplib.h>.
However, this showing build errors in Visual Studio.
Error:

Error	C1083	Cannot open include file: 'openssl/err.h': No such file or directory (compiling source file C:\MITK_ws\MITK\Modules\Segmentation\Interactions\mitkMonaiLabelTool.cpp) [C:\MITK_ws\MITK-superbuild\MITK-build\Modules\Segmentation\MitkSegmentation.vcxproj]	MITK-build	C:\MITK_ws\MITK-superbuild\ep\include\httplib.h	260

Similarly, there are also other errors showing trouble opening ssl.h, evp.h etc.
Not sure why it happens. The CMake variable OPENSSL_INCLUDE_DIR aptly points to C:/Qt/Tools/OpenSSL/Win_x64/include where there is an openssl folder and all header files.