If you edit your profile on what ever your chosen platform or app is, you should see a field like "Bitcoin Lightning Address".
You can enter any email like payment address you have, either the one you'll have from Fountain or perhaps you have a "Wallet of Satoshi" account.
It can be anything you use. You can move funds in and out it from any other wallet you like.
If you don't have a wallet, then
is probably the easiest to setup, once done, you'll have an address like: mikeh@coinos.io to receive funds to.