To share a Presentation online or download it into PowerPoint, go to Presentations (top bar) and select the presentation to be shared or downloaded. 

Click on the presentation to open and edit it, or click on the three dots ( bottom right of the presentation), >Edit

Once in the presentation:

• to download to PowerPoint, select the download button (top right), as shown below.

• to share the presentation online, click on the Share button (top right) as shown below.