Ikea Synfonisk Gen2 remote: How to pair?

I can’t figure out how to pair my Ikea Symfonisk Gen2 remote (W2212) with HA/ZBT. Do I hold down the “chain button” on the back, or click it a certain number of times, or do I use any of the other buttons?

Quickly click the sync button on the back/inside four times (or is it five?), same way as any other IKEA remote