Google makes it difficult to sign-up for an ad account without adding a credit card. You may want to use some of the free tools on Google Ads before signing up for an account. If you are interested in accessing a google ads account without adding a credit card, follow the steps below.
1. Select New Google Ads Account (step one may look different, but select some variation of New Google Ads Account)
2. Click 'Switch to Expert Mode' (will appear at the very bottom of the page - do not click 'Next')
3. Click 'Create an account without a campaign' (this is a link right below the table)
4. Click 'Submit'
5. Click 'Explore Your Account'
6. You should now be able to use Google Keyword's Planner and explore the interface without having added a credit card.