Once you've created a playlist, you can add files to it using the following methods.
Method 1: Adding from the Files tab:
Go to the Files tab.
Select the file(s) you want to add.
Click the Playlists button.
In the pop-up window, choose the desired playlist and click Add to complete the process.
Method 2: Adding directly from the playlist
Go to the Playlists page.
Click the three dots next to the desired playlist on the left sidebar, then select Add files.
Alternatively, use the Add files option in the top-right corner of the playlist.
Select the file(s) by checking the box next to each one.
Click Add to finalize.
