Paste this command on the ubuntu terminal, that will create a keys folder for you containing public key , public key hex and secret key.
casper-client keygen keys
Paste the keys folder created by the above command to JsClient/StakingRewardsFactory, JsClientForFrontend/StakingDualRewards and JsClientForFrontend/StakingRewardsFactory and folders.
We can fund the keys from casper live website faucet page on testnet.
Link:
https://testnet.cspr.live/tools/faucet