Hey there
The article How to Share Content Between Worlds describes the process to follow.
From what you’ve said, I think you’re doing the right steps but possibly in the wrong order.
You should create the Shared Compendium module for the Rollable Tables first, then activate as a module in your original world.
In your original world, export the tables to your Shared Compendium module’s Rollable Tables compendium.
Then, those Rollable Tables will be accessible in any world where you activate your Shared Compendium module.
Hope that helps!