Can you re-check if you have correctly included the kite cpp client folder in your project folder(from where you are making the request)? You can go through cpp example here.
I couldn't reproduce this on two completely different machines running different distros (Fedora, Ubuntu). That enum code represents an SSL error, particularly SSL server verification error. Make sure you are on master branch and you're linking openssl properly. Check your firewall too, it could be blocking connections, but that is unlikely. What is the openssl version you are on?
You can go through cpp example here.
[100%] Built target example1
$ ./example1
Running..
Login URL: https://kite.zerodha.com/connect/login?v=3&api_key=enter_api_key
Login with this URL and obtain the request token.
Enter obtained request token: enter_request_token
Failed to send http/https request (enum code: 10)
As you can see guys it is generation failed to send error . Which means it cannot send the request form the system.
My working directory
$ ls -ltr
total 3220
-rw-r--r-- 1 root root 988 Mar 17 17:03 CMakeLists.txt
drwxr-xr-x 2 root root 4096 Mar 17 17:04 cpp-httplib
drwxr-xr-x 2 root root 4096 Mar 17 17:04 fmt
drwxr-xr-x 2 root root 4096 Mar 17 17:04 PicoSHA2
-rw-r--r-- 1 root root 1607 Mar 17 17:04 kitepp.hpp
drwxr-xr-x 5 root root 4096 Mar 17 17:04 rapidjson
-rw-r--r-- 1 root root 18068 Mar 17 17:51 CMakeCache.txt
-rw-r--r-- 1 root root 5121 Mar 17 17:51 Makefile
-rw-r--r-- 1 root root 1656 Mar 17 17:51 cmake_install.cmake
drwxr-xr-x 2 root root 4096 Mar 19 09:44 kitepp
-rw-r--r-- 1 root root 2770 Mar 19 14:17 example1.cpp
-rwxr-xr-x 1 root root 3224920 Mar 19 14:19 example1
drwxr-xr-x 5 root root 4096 Mar 19 14:19 CMakeFiles
Can you post your issue in this thread instead?