To add audio, create a content item, select the Media layout, and choose the Single audio content block. You can upload new audio files from your computer, add them from your Audio Library, record it directly with our tool, or use the Text-to-Speech functionality.

Also, you can use the Ctrl+C/Ctrl+V option as well as drag and drop the audio file to the audio block on the course page:

Note: to change and paste with Ctrl+V, you need to highlight exactly the block with the audio:

You can customize the look of the player (select if it will be the player only, the player with title, the player with image, or the player with title and image).

You can add and resize a picture from your PC, from the stock, or from your account library.

.aif
.au
.mp3
.ogg
.wav

If your audio has a different format, you can convert it to one of the supported formats using free online tools such as media.io, Online Audio Converter, etc.

Check out Audio Upload Guidelines for more details.