Fatal error: 'openssl/ssl.h' file not found on macos

Do you happen to have the full log for the install? I’m interested in the output from configure, which should look something like this:

mongodb was configured with the following options:

Build configuration:
  CC                                               : cc
  CFLAGS                                           : -g -O2 -O0
  CPPFLAGS                                         :  -DHAVE_CONFIG_H
  Extra flags                                      : -g -O0 -Wall
  Developer flags (slow)                           :  -Wmissing-format-attribute -Wduplicate-enum -Wheader-guard -Wlogical-not-parentheses -fno-omit-frame-pointer -fno-optimize-sibling-calls -Wlogical-op-parentheses -Wpointer-bool-conversion -Wbool-conversion -Wloop-analysis -Wsizeof-array-argument -Wstring-conversion -Wno-variadic-macros -Wno-sign-compare -fstack-protector -fno-exceptions -Wformat-security -Wformat-nonliteral -Winit-self -Wwrite-strings -Wenum-compare -Wempty-body -Wparentheses -Wimplicit-fallthrough -Werror -Wextra -Wno-unused-parameter -Wno-unused-but-set-variable -Wno-missing-field-initializers -Wno-deprecated-declarations -Wstrict-prototypes
  Code Coverage flags (extra slow)                 : 
  libmongoc                                        : Bundled (2.0.2)
  libbson                                          : Bundled (2.0.2)
  libmongocrypt                                    : Bundled (1.14.1)
  LDFLAGS                                          : 
  EXTRA_LDFLAGS                                    : 
  MONGODB_SHARED_LIBADD                            : -Wl,-rpath,/opt/homebrew/Cellar/openssl@3/3.5.0/lib -L/opt/homebrew/Cellar/openssl@3/3.5.0/lib -lsasl2 -lresolv -Wl,-rpath,/opt/homebrew/opt/zstd/lib -L/opt/homebrew/opt/zstd/lib  -lpthread -pthread -lz -lzstd -lssl -lcrypto -lpthread -pthread

From what it looks like, the configure script detected or was instructed to use OpenSSL, but the headers couldn’t be found. Did you install openssl using brew at all?