Banjo add-on trouble

Hello,
I have purchased the banjo add-on sound pack and it installs fine, however, when Notion starts up it says it doesn't have the banjo sound.
I checked in the Notion folder within the Application support folder and the banjo file is in the correct extension folder - I have quit Notion and re-opened it but it still says the banjo sound is not there.
I'm wondering how to solve this problem?
I have purchased the banjo add-on sound pack and it installs fine, however, when Notion starts up it says it doesn't have the banjo sound.
I checked in the Notion folder within the Application support folder and the banjo file is in the correct extension folder - I have quit Notion and re-opened it but it still says the banjo sound is not there.
I'm wondering how to solve this problem?