If you don't mind I would like to ask what service you offer to your users why would you pay them?
Maybe
BTCpayserver can help you about paying your users the best thing about using BTCpayserver is that there is no 3rd party you can host this with your own machine unlike other wallets or services online they do have control of your wallets.
And how did you end up using block.io if you can do it manually with your wallet unless you want them to automate withdrawal in your own website where your users requesting for withdrawal or payout so BTCpayserver is the right choice for this and they do support LTC.