If not, you may find that you've missed a step. If you have followed this step by step you might need to migrate this manually by accessing the files within Aperture. You would do this by right-clicking on the Aperture library and then Show Package Contents. There you will find folders with the Master images and Edited images... you would need to copy the files to your drive and then import into your Lightroom Classic catalog. If you're unfamiliar with this process you may want to have someone help you. It not that it's hard to do - but it is not obvious either.