In order to grant access to locked payment methods to individual users please first make sure that the Unlock via Order Meta settings is set to Yes on the plugin’s settings page:
With the unlocking strategy active you can now find a new metabox on the Edit order screen. The metabox is aptly named Locked Payment Methods and provides you with checkboxes to allow the customer to pay for the given order using normally locked payment methods.
In some cases, the customer might already be unlocked for certain payment methods via another strategy. If that is the case, the checkbox for said payment methods will be disabled and a helpful message explaining this will be displayed (just like for the first checkbox in the image above).