To convert your Canva presentation to PowerPoint, select the three dots on the upper right corner of the editor screen. Next, select ‘Microsoft PowerPoint.’ Your presentation will automatically be converted into a .pptx file.
source : https://www.canva.com/create/powerpoint-alternative/
Canva is a completely web-based design platform so you won’t need to download or install any software to get started. And, since your designs are saved on the cloud, you can access them anytime from any laptop or desktop.
If you want to bring your designs with you on the road, Canva is also available on iOS and Android mobile devices. Just head over to the App Store to get Canva for iPhone and iPad or to Google Play to get Canva for Android for free and start designing on the go.