To use WL, the WL functionality should be enabled for your account.
After the WL has been enabled, you can use the steps mentioned in the below link to upload WL and screen against them.
Kindly note the upload of WL can be done using two ways.
1. Using the UI
2. Using the API.
However, the client can be given only one way of uploading WL to their account. The steps mentioned above is to upload the WL using the API and screen against the WL.
You can upload the WL, only when it is enabled at our end. Kindly note in order to enable the WL, please confirm how you would like to upload your WL using the WC1 User Interface or the WC1 API.
The screenshot you shared does not allow you to upload WL, but is for the purpose of selecting WL while screening so that the entity name being screened gets hit from the uploaded WL too apart from the WC1 DB.
@andrew.lee This is to inform that the WL UI has been enabled in your account.
Please follow the instructions in the link below on how to upload WL using UI and screen against the WL using the API.