Making projects with C on a Windows Machine in College - Works Perfectly
Trying them on my Linux machine at home - errors on 20 lines

Did you use conio.h or Windows API? Windows specific things aren't portable.

@Fast-Nop Those are understandable. But I had most errors on getch()

@HAliPunjabi and where is getch() declared? In conio.h usually.

@Fast-Nop you learn something new everyday

Try this on Linux as replacement:

#include <stdio.h>
#include <termios.h>

static struct termios old_term, new_term;

/* initialise new terminal i/o settings*/
static void initTermios(int echo)
{
tcgetattr(0, &old_term); /* grab old terminal i/o settings */
new_term = old_term; /* make new settings same as old settings */
new_term.c_lflag &= ~ICANON; /* disable buffered i/o */
new_term.c_lflag &= echo ? ECHO : ~ECHO; /* set echo mode */
tcsetattr(0, TCSANOW, &new_term); /* use these new terminal i/o settings now */
}

/* Restore old terminal i/o settings */
static void resetTermios(void)
{
tcsetattr(0, TCSANOW, &old_term);
}

/* Read 1 character - echo defines echo mode */
static char getch_(int echo)
{
char ch;
initTermios(echo);
ch = getchar();
resetTermios();
return ch;
}

If you're on Windows 10, you can use WSL to use the gcc compiler. That's what I do