???It isn't exactly possible for them to do that right now.
The only way colonists are coming to Vinland is via Greenland, which is close buy, and the only way to get to Greenland is to go to Iceland.
If someone wants to colonize Vinland they would need to take Iceland and Greenland before they can even think about getting to Vinland.
Once the technology comes around for crossing the ocean though in the late 1400's that is a different story.
What technology? Norse ships were adequate for crossing the North Atlantic. Knarrar better than Drakkar obviously, but adequate. What do the intervening years give us. Rudders vs Steering oars. That's more important if you're trying to manoeuver. Better sails for sailing closer to the wind. Yes, that would help, but Norse ships were a lot better than most square-rigged ships. Compass. That's only necessary if the weather is so bad you can't tell where the sun is.
People keep saying that Norse ship tech needs to be improved, but they had the best ships in Europe at the time, and made amazing voyages regularly. Sure modern ship tech might allow TRADE (i.e. regular commercial traffic) rather than 'a few ships a year', but you don't need that 'cheap' traffic for Vinland to be viable.