For every 100 transactions performed on a Hedera testnet, you’ll receive 5 hbar in your Hedera mainnet account. The testnet and mainnet accounts must be both associated with the same Hedera Portal profile.
Note: Any tokens that are provided or accrued within your testnet account are 'virtual' tokens to be used for development purposes and it cannot be paid out or transferred to your mainnet account.
Developer testnet activities are just another way to earn hbar towards your existing cap in the community testing program; you will not earn any hbars above and beyond your mainnet cap. For more information on the token earning caps in the community testing program, please see: https://help.hedera.com/hc/en-us/articles/360000664958/