You are accessing the dataset directly. You need to access it via the DataLoader object, for the transforms to be applied.
For example, you could do:
next(iter(dl))

This should return a Tensor to which transforms have been applied.
More generally, to iterate through your dataset, do:
for i, sample in enumerate(dl):
    print(sample) # Or any other processing you'd like to perform

Aside
Your usage of LinearTransformation() appears to be inconsistent with the latest API. LinearTransformation() expects a transformation_matrix and a mean_vector. It seems like you’re providing only the transformation_matrix.