Playlists are saved on Yandex servers and are accessible to users from various computers. This means that you can, for example, create a musical mix at home and then listen to it and edit it on your work computer. However, you will need to log in using the same username that you used to put the mix together.
Each playlist can contain up to 10,000 tracks. There is no restriction on the number of playlists you can create.