Using mtftar to open and convert .bkf files created by ntbackup to tar format

I am trying to open some old backup files created under Windows using ntbackup.exe

I have tried running ntbackup under wine, and ntbackup under Windows 10, both without success as the .dll files necessary are undefined, and seemingly incompatible.

There is a utility mtftar that will convert a .bkf file to a tar format. I am not having much luck with that.

I am running Linux Mint Cinnamon.

Downloading from github : https://github.com/geocar/mtftar and changing the include in tar.c to include <openssl/md5.h> I get the following:

/mtftar_master$ make
cc -Doff64_t=__off64_t -c -o tarout.o tarout.c
tarout.c: In function tarout_md5':
tarout.c:59:2: error: unknown type name md5_state_t'
59 | md5_state_t state;
| ^~~~~~~~~~~
tarout.c:60:2: error: unknown type name md5_byte_t'
60 | md5_byte_t digest[16];
| ^~~~~~~~~~
tarout.c:61:2: warning: implicit declaration of function md5_init' [-Wimplicit-function-declaration]
61 | md5_init(&state);
| ^~~~~~~~
tarout.c:62:2: warning: implicit declaration of function md5_append' [-Wimplicit-function-declaration]
62 | md5_append(&state, (const md5_byte_t *)tf->filename, strlen(tf->filename));
| ^~~~~~~~~~
tarout.c:62:28: error: unknown type name md5_byte_t'
62 | md5_append(&state, (const md5_byte_t *)tf->filename, strlen(tf->filename));
| ^~~~~~~~~~
tarout.c:63:2: warning: implicit declaration of function md5_finish' [-Wimplicit-function-declaration]
63 | md5_finish(&state, digest);
| ^~~~~~~~~~
make: *** [<builtin>: tarout.o] Error 1

My knowledge of C is not up to interpreting the errors/warnings.

Any clues as to the way forward?