Since the platform does not exist within the Bitcoin blockchain, it needs to be tokenized/converted into a pegged/supported token of bitcoin. It is required because of how the way defi itself interacts, they can only talk into their own bitcoin token, not the real bitcoin on the Bitcoin blockchain.
The way of the mechanism work is the platform, which, in this case, Sovryn or ALEX can only comprehend the systemized token of the bitcoin, hence, your fund/coin(bitcoin) needs to be converted.