Crits? But you know already.
You are an amateur lacking will to succeed. I also don't believe you are very intelligent person, otherwise reason would prevail.
Sky is boring, empty. Illustration is not just a copy/pasting of visible realm but showing, sharing emotions. Even photographers know it.
Texturing is bad, repetition and some obvious seams. Learn splatting...
Darks are too dark, black. There's no 0-0-0 black except in singularity (black hole), every other matter gives some photons back. As there is no pure white material.
Looks as if no effort invested, even if it was built in a day (and under stress)... shows lack of skill, practice and experience.
Seems the project was finished before you started it (a prejudice).
Learn basics. Get to know foundations of art, aesthetics... feelings, pain, pleasure & joy. All shared via medium of light. Experience the catharsis.
To master any artistic skill, stay mentally strong, do your best or simply say no, before tickling the demons.
While working with clients, it is not clients fault for miscommunication, it is artist that is def.
;)
have fun in life