I just used the free version of Adobe Express to create a 30 slide slide slow(which appears to be the maximum). While I see hints about people attaching music to videos I am still not certain if the same can be done with slide shows. If the answer is yes, can you point me to some directions.
In an Adobe Express Video project (where you create slides), in the upper right corner is a Music option. Click Music to choose from multiple types of music to add it to your slides. Here's more information: