When creating Facebook Link Ads with Cobiro, the daily budget for the ads you will enter within the setup process.
An overall total amount will also be displayed and this total will be linked directly to the duration the ads will run for. For example $5 a day for 30 days, Maximum Budget: $150.
The daily spend on the ads can be up to 25% higher than the daily budget. Facebook does this is to allow and optimize the ads when they ads have more opportunities to get results For example daily budget of $100, Facebook may spend $125 shows these ads
But you will never spend more than their ads overall budget. More information about Facebook Daily Budget can be found here.