Welcome to the forum!!
So, if you are loading a Gcode(TAP file) and it’s outside the dimensions of your table what you are trying to cut is drawn at a larger scale than you can handle… The TAP file is basically finished… Although it may be good for one person and their cutter, it may not be for you…
In Mach3 you can scale a TAP file down where I’ve circled…
You might try to enter a value of .5 in there at first and then RE-GEN toolpath to see if it fits at that point… You can play with it from there…
Let us know if this works for you…