The web based version of PowerPoint has limited functionalities.  

The Export function is only available if the application is installed on your device. 

Click here for a guide on how to install Microsoft 365 applications.

 Export as a Video

  1. Go to File > Export.
  2. Select Create a Video.
  3. Choose the video quality (e.g., Full HD).
  4. Set the timing for each slide if needed.
  5. Click Create Video and choose where to save it.


Microsoft - How to save a PowerPoint as a video