EVs should be charging at night, and they should be charging off-peak rates to do so. Some cheaper cars like the Nissan Leaf don't have enough capacity to make it through the day without charging.

This is a temporary problem. If a car has 200 miles of range (teslas have at leaat 230) and its only used for 60 miles per day (even in -40F conditions), nighttime charging is still on the table. Off-peak power can be as much as 1/3 to 1/4 of peak, so there is incentive to do so, particularly for transportation.

The article discusses grid limitations, not generation limitations, though it may be a factor at the moment and they are bringing online a new plant to meet demand (according to the article).

Alberta is a very cold continental place, and consequently, the majority of its population is concentrated in Calgary (much like other metro-areas like Toronto, St. Louis, Kansas City and Minneapolis.) This can be a challange for the electrical grid to meet peak demand. There simply isn't much real-estate to put new subatations. Some urban substation locations have original buildings from over 100 years ago with asbestos and knob & tube wiring throughout. The cost, and impact on "five nines" uptime of running new, higher voltage and lower-sag wires in a city makes upgrading often a pipedream.

So yes, places like Calgary where the population isn't being driven out of dense urban areas by forced integration from hostile nations and psyop-driven race-baiting because the government isn't insane like most western governments, it can be a challange to meet demand for electricity from a more economical means of transportation.