It is the temperature range in which the body doesn't shiver or sweat, but has an idiomatic sense of a place where people feel comfortable, where they can avoid the worries of the world. It can be physical or mental.
Do what is required, come up to expectations. For example, Kate delivered the goods and got us the five votes we needed. This phrase alludes to delivering an order of groceries or other items. [Colloquial; second half of 1800s]