There is, however, a limit of 10,000 songs that can be added to one playlist.
And you should also consider that the app performance might be affected, if you have a high number of playlists. We therefore recommend keeping the number below 2,000.
Another thing to keep in mind is that you can download up to 10,000 songs on a maximum of 5 different devices to listen to offline. For full information on this, we recommend you check out this support page.