Register company or register a company?

[micca]

There is one rule of articles I am a little bit confused about that is related to not writing articles when the noun is a part of an action. For example it's "go to school" and not "go to a school".

So does this rule apply here or not, "register (a) company" or "log in (a) user"?

[Alan]

The article is required in both cases.

'Go to school' is an unusual exception to the general rule.