How to fix configure error for FFTW-2.1.5 on an M1 MacBook Air?

Question

I'm trying to install fftw-2.1.5 in order to run GADGET2. On my M1 MacBook Air it crashes at the configure step.

I have tried the advice on This overflow post But as i am new to Linux i am having a hard time with steps 2 and 4.

Here is what i am running to try and configure:

./configure

And this is the error i receive:

configure: error: /bin/sh ./config.sub -apple-darwin23.1.0 failed

When trying to patch the files using the files on Debian I am able to create and run a patch file, but i do not know what to put as the location to patch?

I am running this patch file from Debian:

Author: Paul Brossier
Last-Update: 2008-05-14 11:23:40 +0200
Description: Workaround gcc-4.1 bug

--- fftw-2.1.3.orig/tests/test_main.c
+++ fftw-2.1.3/tests/test_main.c
@@ -548,7 +548,7 @@
 void test_timer(void)
 {
      double times[32], acc, min_time = 10000.00;
-     unsigned long iters, iter;
+     unsigned long iters = 0, iter;
      fftw_time begin, end, start;
      double t, tmax, tmin;
      int last = 0, i, repeat;
@@ -559,7 +559,8 @@
      start = fftw_get_time();
 
      for (i = 0; i < 32; i++) {
-     iters = 1 << i;
+     //iters = 1 << i; /* workaround gcc-4.1 bug */
+     if (i) iters <<= 1; else iters = 1;
      tmin = 1.0E10;
      tmax = -1.0E10;

I then run,

% patch < Patch_1.sh
can't find file to patch at input line 7
Perhaps you should have used the -p or --strip option?
The text leading up to this was:
--------------------------
|Author: Paul Brossier
|Last-Update: 2008-05-14 11:23:40 +0200
|Description: Workaround gcc-4.1 bug
|
|--- fftw-2.1.3.orig/tests/test_main.c
|+++ fftw-2.1.3/tests/test_main.c
--------------------------
File to patch: 

And I am unsure how to continue.

Also whilst attempting step 4 from the original post, I run this,

% autoupdate

And receive this error,

zsh: command not found: autoupdate

I am also unsure of what i am doing wrong here.