Make Discord server membership optional, not mandatory

I want to be able to connect our Discord server to Rubric, but I don't want to force every single person who joins our Discord to buy a membership. It would be great if we could make membership optional, or perhaps only require it for specific channels or categories within the server. This would lower the barrier to entry for new community members and allow us to have a mix of free and paid members in the same Discord. Forcing everyone to get a membership is too controlling for our club.