Garmin or phone mounting on Silverback bike - Fouriers bracket

[mnz]

So, the eMTB I got is a Silverback S-Electro Pro CF1 and they advertise a Garmin / Phone mount on the top tube. But I have no idea how to connect a Garmin mount to it, anything... SP-connect, quadlock... something for the phone...
Maybe you guys have some ideas how to fit something.
Ideally I would put a quadlock something on it because I already have the iPhone case. But I don't even understand how they connected the Garmin we see in their pictures. Their Customer Support told me to fit this onto the existing bike mount, but it seems like a bad joke.

Here's how it looks on the bike:

 

[Arethustra]

Looks like you need a quarter-turn female like this but you seem to be missing the outside holes to attach the adapter.

 

[mnz]

Better late then never, I'm back with an update:
I tracked this down to the Fouriers Brand of Bike Mounts and I ordered this from aliexpress

It fits perfectly. Apparently Fouriers uses this type of "middle-screw + outside pin" (to prevent rotation because it's only 1 screw, not 2). The 2 outside pin holes that I have on my bike allow mounting the bracket in 2 separate positons: "landscape" and "portrait".
Problem solved.