You can create a credential at the team level in Tines. A credential will only be available in the story when it is created for the team in which that story resides.
Select the team you wish to add the credential to
Click "New Credential" and select the tool you are connecting to or the type of credential required.
Each type of credential requires different information. Complete the required fields. You can find more details of the different types of credentials here.
The credential is now available for use in the stories in the team.