The character must select a corp wallet division by opening their wallet, going to the Corporation Wallet tab, and selecting Change Active Division button at the top.
EDIT: Never assign individual roles. That way leads to errors, and is hard to maintain. Instead, create title(s) with roles and assign multiple titles as necessary. Example title: ‘Industrialist’.
You should have a no-role title of ‘Diplomat’ and assign that chars you want contacted for corp affairs, and publish the diplos in the corp info. If there are no diplos, usually the CEO is contacted.
Avoid granting the role of director. Instead create a title of ‘Director’, and assign all roles EXCEPT director. These ‘virtual directors’ cannot declare wars, nor execute any actionable votes that have succeeded (like lockdown, or un-lockdown), but they can do everything else.