Unlike the individual US states, Alberta never joined Canada. It was not an entity that existed prior to Canada's confederation. Alberta was basically pencil-whipped into existence by carving out a chunk of an already existing territory (the Northwest Territory).
Despite American and Russian destabilization campaigns in Canada, there is no legal mechanism by which Canadian provinces can unilaterally secede.
>And that gets a lot more complicated if the US also wants Alberta to go independent....
Recent past polling overwhelmingly showed Albertans in favor of remaining in Canada. This latest frenzy is widely known to be a foreign influence operation.