Install 75 boot cover

Have a new boot cover for 75 convertible but no installation instructions. I can see where the snaps go but not the 2 elastic straps. Does the bottom flap tuck behind the top of the rear seat?

I'm not sure about your year, but in later the seat could be tilted forward at the top. Then there were two rubber stops that you looped the straps over. When the seat went back into position it pressed over the two rubber stops thus securing the straps.