Sounds like it has 3M automotive tape on it. As previously mentioned just clean surface and peel the red tape off and it won’t likely let go once stuck down. There is a channel on the awning side that runs the length of the awning that the weather strip fits into and gravity on the van side is often sufficient to seal the weather strip. It is there to stop the water coming between the van and the awning.
2021 Ford Transit AWD ‘Iron Horse’
Formerly - 2007 Pleasure Way Plateau (06 Sprinter T1N), 1992 VW Eurovan Westfalia Hightop
Long ago - 1969 VW Westfalia & 1973 GMC Motorhome