SoggyBeetle95 you can configure the credentials in the clearml.conf running on the agent machines:
https://github.com/allegroai/clearml-agent/blob/a5a797ec5e5e3e90b115213c0411a516cab60e83/docs/clearml.conf#L320
(I'm assuming these are storage credentials)
If you need general purpose env variables, you can ad them here:
https://github.com/allegroai/clearml-agent/blob/a5a797ec5e5e3e90b115213c0411a516cab60e83/docs/clearml.conf#L149
with ["-e", "MY_VAR=MY_VALUE"]