To activate the XRP and SOLO addresses you need to send 20 XRP or more to it.
Sending an amount less than 20 XRP to not-yet-activated address results in a failed payment. The network also takes a fee for these failed payments.
Why is 20 XRP required?
There is a 20 XRP reserve requirement to activate any XRP wallets. Once an XRP address is funded with the 20 XRP, the activation fee will be locked by the XRP ledger network.
The 20 XRP used for activating the wallet can be retrieved. Please note that the retrieval cannot be processed through the SOLO APP.
You can watch SOLO Wallet App v0.5 | Step-By-Step User Guide here: