Whether or not you can access or download the slides (and your notes) after a presentation has finished is determined by the presentation permissions set by the presenter. If the presenter is happy for their slides to be downloaded (along with your personal notes), you will be able to download them from the DOWNLOAD tab.
Whilst the presentation is live you can activate the Send me the presentation toggle and you will be sent an email with the slides and your notes once the presenter ends the presentation.
Once the presentation is over this will become a button and you will be sent the slides and your notes instantly.
Information on turning on downloads for slides and notes can be found here.