To begin, you need to make sure that your Prezi presentation is set to Public & reusable. To do this, log in to your Prezi account, choose your presentation, and click this button.
Once done, click on Embed, found to the left of the Public & Reusable button. Using the pop-up menu, you can specify the size of the Prezi, as well as whether you want to restrict your learners to following the animation flow that you chose, or whether they are free to pan and zoom the presentation as they see fit. Once done, click Copy code to clipboard.
Next, return to your SkyPrep platform, click on Teaching then on Materials. Click +Add Materials at the top right.
Choose Embed Link. Paste the code that you copied into the Content section. Once finished editing the settings, hit Add Link at the bottom.
Now you can use your Prezi presentation the same way you would use any other Material!
When your learners launch the presentation, all that they have to do is click Start Prezi.
They will then see the presentation at the size that you specified originally, with the option to make the view fullscreen by clicking the button on the bottom right of the presentation.
Here is the view with the default sizing:
And here it is in fullscreen: