They can't.

1. Corporations aren't allowed to donate to politicians at all.

2. Foreign entities aren't allowed to donate, either.

Donations "from a corporation" are really donations from employees of the corporation. That is commonly misrepresented in news reports. You're required to cite your employer so that it can be spotted if the employer is filtering corporate donations through individual employees -- as was the case here.

American Corporations can create political action committees that are allowed drastically limited political donations. More importantly they can spend unlimited money on "issues" as long as they're not directly coordinating with a political campaign -- a fig leaf that can be less than a single atom thick at times.

“American corporations” is also less than an atom thick, as there are many fewer requirements than citizenship, for instance. There is no requirement for an American company to be owned by an American.