How does it work to actually be considered for disability?

Mom has obstructive Obstructive Hypertrophic Cardiomyopathy, can’t do any part of her laborious health care job without heart symptoms. Been on unpaid leave for almost a year and her EI sick leave ran out a couple months ago. Recently she told me her cardiologist said she wouldn’t qualify for disability because she could do administrative work instead, but she just isn’t fit for that, her english is low and for her whole adult life her occupation was strictly her patient home care job, that’s all she knows. so what happens if they attempt to accommodate her but it doesn’t work out? They fire her or? Because she can’t do her typical occupation.