Mad Muscles Meal Plan Assistance

Hello, I am on day 1 of the Mad Muscles Meal Plan. Some questions,
1. Can I substitute a vege if I don't care for what is listed?
2. Can I skip a snack?
3. Can I reduce quantities?
4. How important are portion sizes?
It is a little challenging for me to eat the quantity of food being recommended and I could use some support with rationalizing it.
Thanks

1. Yes if the total calories are about the same and the total macros meet sufficiency
2. Yes if the total calories are about the same and the total macros meet sufficiency
3. If that means your total calories are lower, you may reduce your surplus or increase your deficit - is that desirable?
4. Very. Because they determine the total calories and the total macros

Fixed meal plans are often not suitable. Perhaps post your stats and preferably some pictures. Tell us your goals. Then also post how many total calories are in this meal plan.