To use credits from your Gengo account for translation orders on POEditor, you need to have a POEditor organization and an Enterprise subscription on it.
The setup is very easy. First, go to the Gengo website in Settings > API Settings and get your Public Key and Private Key.
Then go to your POEditor organization settings in Organization > Third-Party Access and click on Enable for the provider Gengo.
Add the keys from your Gengo account, save them and you're all set. You can now order translations for your localization projects using your pre-paid Gengo credits.
If you need to add more credits to your Gengo account, you can do that in your Gengo account Settings, in the section Top-Up.