Those Jackets look like a bargain moondog.
I should have said 'Snap', rather than 'snap lock' (which would work as well if you wanted to sew a strap on).
The metal ones use a punch which may be the cheapest option:
https://www.ebay.com.au/itm/40pcs-Snap- ... 2749.l2649So.. punch a snap (eg the male side) through, around the label somewhere/ inside below the collar and trap a strap of some sort with the snap. Put some sealant on the snap before closing it down Then put the alternate snap (eg. female side) on the end of the strap making the strap an appropriate length to hold the rolled up collar.
I've used 'similar' to pull a hood back further rather than a rolled up hood. I'll grab a pic if you are still (or more) confused?