The Valk' has weird voltage and needs some kind of setup to run 12volt systems. There is a way to do it but it isn't as straight forward as buying some mirrors with indicators and hooking them up.
It's possible the Admore adapter could be used to enable the mirror signals to function properly.
You can wire 2 relays to power the 12v signals. Use the 5v to the bike's signals to activate the relay.