20 FS on Book of Dead will likely give you small win only if we look at the nature of this slot which is rare to give big win in normal spins.
Actually the free spins awarded are 200 , not 20, that and assuming each spin is worth $0.1 this promo can be considered basically as a 100% deposit bonus with a wagering requirement much lower than the market standards.
My bad, I thought it is 20 LOL seems that I focused on the min deposit requirement only.
In terms of value, yes 200FS equal to 100% deposit bonus but of course we know that the outcome of the free spins is always unpredictable.
It can be 100%, it can be more, it can be less or maybe it can be nothing as well.
Back to the KYC, you should be ready for it because when it comes of promotion and players are able to make profit, the chance to be asked for KYC is bigger.