The daily 2.5% gain is not automatic. First you need to own Corion coins. The emission is based on the exchange between COR and USD. Anytime the rate goes above 1 USD coins are released to balance the price.
Each 3 hours the price of Corion coin is checked (automatically by the system) and If the price of COR is above $1, then 0.3% new coins are released to balance the exchange rate.
How do you gain:
If you own 1000 CORs, then you get 0.3% of 1000 = 3 CORIONS, but you have to be connected to a service provider to claim the released coins. The Providers keep part of the realeased coins. Many service providers give 70%, so 70% of the 3 CORs is about 2 CORs. This can happen every 3 hours if the price stays above $1 so 8 x 0.3% is about 2.5% a day and can be for 1000 CORs about 16 new CORs in your wallet.
No gain received
It is possible that the price of COR stood below 1USD so there is no emission therefore no gain available.
The other possibility is that you haven't connected your wallet to a Provider. You must do so to be able to get your gain as described above.
As each claim is a transaction on the blockchain, there is a transaction fee to be paid. This is also valid for the claims zero emissions.