There is no minimum amount required to make a transfer with YouTrip Send, as long as your wallet contains a sufficient amount of the currency you intend to transfer. If you don't have enough of that currency, make a top-up or in-app currency exchange.
The maximum transfer amount is S$5000 (or its equivalent in other currencies), which is also the maximum a YouTrip wallet can hold at any point in time. Accordingly, your transfer will be automatically blocked if the amount transferred causes the receiver's wallet balance to exceed this wallet limit of S$5000 (or it's equivalent in other currencies).