There is no official digital release. However, fan-created communities have begun digitizing the audio cassettes (with varying degrees of hiss removal). A quick search on private language-learning trackers or French nostalgia forums may yield MP3 rips, though their legality is dubious.
The series was spearheaded by Laetitia, who often worked under the pseudonym Anaïs. She operated both behind and in front of the camera, a rarity in the industry at the time. L--ecole de Laetitia -vol. 1 Et 2 -1994-