@Hassey I know this is from ages ago, but it basically means that you should make really sure that the colours are really different enough from each other. The automated warnings are not perfect.
@Hassey The green box is just a notice that while the pattern already exists, you can add a variation with different colors. All you have to do to submit your variation is click on “submit to the site” button.
How do you submitted the pattern? I've submitted a pattern with the same colors but a green box with a attention says 'If you want to submit the pattern in this state, please double-check if it is ok. Thank you!'