Let’s say I have this title:
How to Install a PHP Extension: Quick and Easy
Should I say quick and easy or quickly and easily?
The terms Quick and Easy modify Install. Technically, since install is a verb, they should be adverbs - Quickly and Easily.
However titles have a life of their own, and they often exist on a different planet than we prescriptivist grammarians. You get a lot of latitude.
Additionally, the adjectival forms have an implied noun to modify: installation. You are suggesting the installation will be quick and easy.
To be a purist, make them adverbs. Or you can leave it punchy.
Your are modifying an infinitive so you need adverbs, so you'd be on unassailable ground with Quickly and Easily, but Quick and Easy might be snappier in a title. You could make the issue disappear with either "PHP Extension Installation, Quick and Easy" or "Quick and Easy Installation of PHP Extension."
"Quick" is an adjective and "quickly" is an adverb, so you should use "quickly" to modify "do".
However, "quick as possible" is often used in everyday English.
But I suggest you to use fast and easy. See this link.
Quick can be adverb or adjective.