I am a web developer and was working on a website that is in both German and English. As my partner (native German speaker) and myself (native English speaker) were looking through the site he noticed a capitalization error in the German version. He then switched to the English version and asked me if the way I capitalized the call to action is correct, in English.
In this case, the phrase is Request a Quote.
To better understand how it is presented, below is a screenshot:

My thought is that call to actions should be treated like a title. Is this correct? Should call to actions be capitalized or should they be lowercase (Request a quote)?