The thrust of it is that the federal government would withhold funding to municipalities unless they meet certain home-building targets.
Critics worry that this will accelerate suburban sprawl in order to meet quotas. There are some provisions regarding rental housing and transit infrastructure, but with unrealistic time/budgeting constraints.
This is the real issue. Having grown up in a dot on the map in the middle of the Ontario boreal forest on the arctic watershed side of the Shield, I can tell you that it isn’t all that much harder to build infrastructure there than it is further south (sometimes takes a little longer because of longer winters, that’s all). It isn’t even horrible land agriculturally as long as you take the shorter growing season into account when you’re choosing what to plant. So more of the land is usable than you might think. However, people want to go to the places where people already are.