Change the outputFolder variable to the location of your dataset:
outputFolder = 'path to your dataset';
Let's say that within that folder, the images and stored in folder called "images" and labels in folder called "labels"
imgDir = fullfile(outputFolder,'images');
imds = imageDatastore(imgDir);
labelDir = fullfile(outputFolder,'labels');
The classes may change in your case, so you have to make changes accordingly and use the pixelLabelDatastore to load the labels.