You can save texts in a playlist as one audio file (mp3). Audio file creation is a paid feature.
Open the menu
On the reading list screen, tap the playlist name at the top (for example, Voicepaper).
Create audio from the playlist
In the menu, tap "Create Audio from Playlist." A filename input screen opens. Rename it if needed, then tap "Start."
After creation
A progress indicator appears during creation, and a share sheet opens when it finishes. If the playlist is empty, creation is unavailable, so add texts first. On the free plan, an upgrade prompt appears.