If you see a transaction in your transaction history listed as “not sent,” please consider the following:
Are you sending XRP? If so, please know that XRP requires all users to hold at least 10 XRP at all times, this is known as the reserve. Both the sender and receiver are required to meet the reserve so if sending to an empty XRP account, the minimum to send for a successful transaction is 10 XRP. This is a feature of XRP and is not something that Arculus can control.
Are you sending ERC20 coins or tokens? If so, the gas fees for ERC20 transactions are paid from ETH. Please make sure you have enough ETH to cover the gas fees for the ERC20 coin/token sends.
If neither of the above situations apply, it is possible that the request to send expired before it was picked up by the blockchain. You may want to try sending again, but the transaction at a higher fee, if applicable for that network.