Before you proceed, please understand that Lightning Network is still in the experimental stage. Do not put the money you can't afford to lose. There is a high risk of you losing the money.
Take time to familiarize yourself with the risk. There's no backup for LND or c-lightning keys in BTCPay. Your keys are in a hot-wallet. This means :
Most of BTCPay Server deployments run on a pruned node, which, while working, is not officially supported by lightning network implementations.
If you erase your BTCPay Server virtual machine - you lose all the funds.
If your server gets hacked - a hacker can take all of your funds by accessing your keys.
If there is a bug in a lightning network implementation - you might lose all the funds.
You approve being #reckless and being the sole responsible party for your loss.
You approve to keep on your lightning node only what you can afford to lose.