Varicose veins are a risk factor for venous ulcers. That is a connection, and it is worth being precise about what kind.
A risk factor is not a cause in the sense of something that will happen. The full list of risk factors is long: varicose veins; a history of blood clots in the legs; blockage of the lymph vessels; older age, being female, or being tall; a family history of venous insufficiency; obesity; pregnancy; smoking; sitting or standing for long periods of time, usually for work; and a fracture of a long bone in the leg or other serious injuries such as burns, muscle damage, or a large surgery.
The cause of a venous ulcer is venous insufficiency: the one-way valves in the leg veins become weak, or the veins become scarred and blocked, so blood flows backward and pools in the legs. That raises pressure in the lower leg veins, makes it harder for nutrients and oxygen to reach the tissues, and a wound can form.
Varicose veins also come up in a different context. Poor blood flow is one of the factors that can prevent wounds from healing or slow the process, and it may be due to clogged arteries or conditions such as varicose veins.
So varicose veins matter twice: they make a venous ulcer more likely, and they can make a wound heal poorly once it exists.
This page can’t tell you how likely an ulcer is for you, or over what timescale, and it won’t estimate either.
The measures aimed at this are the same ones used for venous insufficiency generally: compression as instructed, feet above the heart as often as possible, daily walking or exercise, keeping the skin of the lower legs well moisturized, not smoking, controlling blood sugar if diabetic, managing blood pressure and cholesterol, and losing weight if overweight.