Had problems bootstrapping Inline module 'bb_pl_d714'

I think you simply need to add the location of the libcurl dll to your PATH, as that dll needs to be located at runtime.
That location is probably:

C:\Users\Administrator\Downloads\curl-7.67.0_4-win64-mingw\curl-7.67.0
+-win64-mingw\bin
[download]

This script (almost identical to yours) worked fine for me on Windows, building against curl-7.65.0-2, as provided by the MSYS2 project:

use strict;
use warnings;
use Inline 'Config' => BUILD_NOISY => 1, CLEAN_AFTER_BUILD => 0;
use Inline 'C' => 'Config' => libs => '-LC:\_64\msys64\mingw64\lib -lc
+url.dll',
                    inc => '-IC:\_64\msys64\mingw64\\include';
use Inline 'C' => <<'CODE';
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#ifndef WIN32
#include <unistd.h>
#endif
#include <curl/curl.h>
int init(){
    CURLM *cm;
     curl_global_init(CURL_GLOBAL_WIN32);
     printf("SUCCESS !!\n");
     return 0;
}

CODE

init();
[download]

After the build completed it output "SUCCESS !!".

Cheers,
Rob