Scaler 2 has predetermined patters called performances. These can be used to create bass lines and melodies, and patterns can be combined using the Playback Performances to create melodies (see Introduction to Using Playback Performances to Give Interesting Melodies
There is no arpeggiator in Scaler 2.8 and I think that @davide is suggesting that new performances will be added in 2.9 when it is released.
Hopefully an arpeggiator/sequencer type functionality will be released in Scaler 3 (it has been requested as a feature request) but there are no details yet of the Scaler 3 functionality.
In the meantime if you just want an arpeggiator then BlueARP is very versatile and free, but does have a quirky interface which can take some time to learn.