I found the issue and the solution. I had to iterate through the sub accounts, the campaigns were not directly to my main account:
function main() {
var accountSelector = AdsManagerApp.accounts();
var accountIterator = accountSelector.get();
while (accountIterator.hasNext()) {
var account = accountIterator.next();
var accountname = account.getName();
console.log({accountname});
AdsManagerApp.select(account);
var campaignIterator = AdsApp.campaigns().get();
console.log('Total campaigns:' + campaignIterator.totalNumEntities());
while (campaignIterator.hasNext()) {
var campaign = campaignIterator.next();
console.log(`${campaign.getName()}; active? ${campaign.isEnabled()}; budget=${campaign.getBudget().getAmount()}`);
}
console.log('Finished listing campaigns.');