What you can do is create a new Sound Cue. In the Content Browser, right click and go to Sounds > Sound Cue.
Give the Sound Cue blueprint a name and then open it.
Right click the graph and add a new Wave Player node. Select the Wave Player node and in the details panel select your Wave sound file to play and check the “Looping” checkbox.
Update your Spawn Sound 2D and change the source file from the audio file to your new Sound Cue class.