You can Export MIDI and Audio files recorded in the app using the Export Files button in the Player window (screenshot included):
Directly working with the app directory in Windows Explorer is not recommended, as you could potentially cause issues in the app by adding or removing the wrong file in the wrong place in the app directory.
However, if you really want to use Windows Explorer to get files from the app, the files are located here:
C:\Users\YOUR USERNAME\AppData\LocalLow\Visual Music Design\SeeMusic
(This folder might be hidden - you might need to Show Hidden Files in the View options in Windows Explorer)
Thank you for replying! I am just thinking of backing them up on my OneDrive by copying, or at least the template for all my videos.