I'm not able to right-click. Even when the buy/sell clicks are inverted, I just can't right-click. How do I fix that?

No reply, I assume this was solved.

There is a ton of missing information here. Please provide all of the one requested in the issue template... but basically you want to make sure that the shop sign isn't in any form of spawn protection or the interaction blocked by other protection plugins.

I am building a SHOP in the reserve
Right-click cannot be used to use SHOP in the protected area
Hope to be able to add the option to modify the button
EX: keyboard S to sell, keyboard B to buy

It is not possible to catch arbitrary keyboard keys from the server, the client doesn't send those. You are going to have to check how to enable shop sign interactions in your protection plugin.

I am building a SHOP in the reserve
Right-click cannot be used to use SHOP in the protected area
Hope to be able to add the option to modify the button
EX: keyboard S to sell, keyboard B to buy