Why can't i buy with Coinbase?

Why is it that I'm unable to purchase cryptocurrencies through Coinbase? I've heard so many good things about their platform and I'm eager to start investing. Is there a specific reason why I'm encountering difficulties or are there any steps I need to take to resolve this issue? I'd really appreciate any guidance you can provide as I'm new to the world of cryptocurrency and want to make sure I'm navigating it correctly.