Need to fasten/glue roofing shingle type of stuff with something that actually hardens

I have this:

https://www.aquaplan.com/product/easy-band/

I need to attach it vertically to some thick hard rubber roofing. There is a small section of roof which should probably normally have a parapit but instead the roofing rubber is not backed by anything. Then below it is a wood panel. So when it rains sideways the water runs down the roofing rubber and behind the wood panel.

I just need a piece of shingle to divert water to the exterior side of the panel. Roofing glues are made to never cure. Probably rightfully so, but that probably wouldn’t work to attach a shingle vertically as gravity would over power that tar-like never fully dry stuff. I tried construction adhesive & it didn’t hold.