You need to submit your credit card details before starting with LinkedIn ads. LinkedIn will then charge you periodically with that credit card. The frequency depends on the daily budget and your total ad spending.
You can control your ad expenditure by setting a daily budget and selecting preferred bidding option. Daily budget will limit your spending per day. You also can limit your cost per click (CPC) or 1k impression (CPM) by setting a maximum bid per action. You will also have the ability to pause your ads any time you want.