I'm sorry you're having troubles with LilyPond. If you tell me what you don't get I (or someone) can help with that.
As a starting point, here's the LilyPond source code you posted, corrected so it will compile, and with the MIDI honoring the repeats:
\version "2.22.2"
\header {
title = “%%%%"
composer = "Omer Katzir"
tagline = "
http://omerkatzir.net"
}
upper = \relative c' {
\time 3/4
\key g\major
\voiceOne
\tempo 4 = 90
b b b b
}
lower = \relative c {
\key g \major
\voiceTwo
\repeat volta 2 { b b b b b }
\alternative {
{ a a a a }
{ a a a a \mark \markup { \italic "Fine" } \bar "||"
}
}
c d e f g a b c \mark \markup { \italic "D.C. al Fine" }
}
\score {
<<
\new StaffGroup = "tab with traditional" <<
\new Staff = "guitar traditional" <<
\clef "treble_8"
\context Voice = "upper" \upper
\context Voice = "lower" \lower
>>
\new TabStaff = "guitar tab" <<
\context TabVoice = "upper" \upper
\context TabVoice = "lower" \lower
>>
>>
>>
%%% Below, tells LilyPond to only create PDF
\layout {}
}
%%% Below, create a MIDI-only score with repeats unfolded
\score {
\unfoldRepeats {
\new Staff <<
\new Voice \upper
\new Voice \lower
>>
}
\midi {}
}