Here is how i chosed? to map the octaves, i can say it wasn't clear to me at all how it should be done, but i felt this made most sense?
I only have 5 octaves on my synth, it probably get more normal howto map with a fullscale "grandpiano?"

Here though they claim 48 is C3 not C4=60
https://www.inspiredacoustics.com/en/MIDI_note_numbers_and_center_frequencies

Of course the mapping is just integers to notes but i am just happy if i can confuse someone 😉
https://www.youtube.com/watch?v=W1TO_tSb8ck
Apparently they are correct i mapped C3 and claim it is C4.

My MIDI equipment is roughly 30 years old. Here's what I know. My Kawai K1-II synth denotes MIDI note #60 as C3. My Alesis SR-16 denotes MIDI note #60 as C3. When I say "denotes" I mean in both the user manual, and on the instrument's display panel.

Now for the reveal. My sequencer is Cakewalk Pro Audio and after recording MIDI output generated from both the Kawai and the Alesis, Middle C appeared (in Cakewalk) to be C5. This confused me. So after much searching in the Cakewalk help system, I found a general global option named Base Octave for Pitches which was defaulting to 0. This option controls the octave value, like the 6 in "Db6". So by defaulting to 0, the lowest MIDI note (note #0, which is a C) is visually displayed as "C0", and consequently visually displays note #60 as C5.

So in order to adjust my software sequencer (Cakewalk) to match the octave values for my instruments, I had to set the Base Octave for Pitches value to -2. Now when I "see" note #60, it displays as C3 in the sequencer, like all my instruments do. Again it only affects what I see in the Cakewalk Sequencer. It does not alter the underlying MIDI note number.

Note the Cakewalk help system mentions the Yamaha FB-01 as an example which uses MIDI note 0 as C-2.

I hope this helps someone. 🙂

Other ancient hardware like my 360 Systems Professional Midi Bass, also denotes MIDI note #0 as C-2, and hence note #60 as C3.