In a UFC no contest result, fighters typically do get paid for the fight. The specific payment terms may vary based on the fighters' contracts and the policies of the UFC. However, it is common for fighters to receive at least a portion of their contracted purse, regardless of the outcome of the fight.
Pleading guilty means you admit that you committed the crime. Pleading no contest ( nolo contendere ) means that you accept the conviction but avoid a factual admission of guilt.