Product was rejected! Help please and give me some advice

Thank you for your submission. We have completed our review of “Engineering Logo” and unfortunately we found it isn’t at the quality standard required to move forward, and you won’t be able to re-submit this item

the illustration part is rather good though not clearly original indeed. Now the color combination is clearly not satisfying in my opinion, since lacking harmony … combining complementary colors would be much much more a good idea indeed or playing with declinations of the same color …
i think it would be better two combine different fonts, at least two, for the title and tagline , this seems to be what they expect here in a general way as regard to typo
it seems that a horizontal version of your logo is missing when u are expected to have it both as a main file and in the preview, besides, accprding to me the preview part displaying all the logos like this is not efficient as spaces need to be introduced so that the preview “is breathing”, at this stage it looks as if there is a road and huge traffic jam inside of it lol