I saw some advertisements; they use "quality materials", "qualified teacher". Is there a rule to use these words. Also there are some words (sports, sales); they are adjective when adding "s". i also saw many words (e.g. communication, admission, student, etc.). They were added "s" and fuunction an adjective e.g. students intake, admissions exam, etc. Is this correct?
The basic answer to your question is that "quality" has nothing to do with "qualified". Have you looked up the definition of both. The only thing they have in common is that they are both adjectives in your examples although "qualified" can of course be a verb in the right context.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.