If it's a fresh account, it might take up to 72 hours in some cases, sometimes even longer (especially if the account and campaign aren't perfectly set up). It might be a message that it's under review, you might have it accepted but it can be off and you'll see the "we can't determine why your ad isn't showing up" message. Honestly Google Ads is a mess and every account is different - really a small percent of all accounts don't have random reviews, stops, bans, or ad rejections. You have to get used to it. For now just wait until it's accepted. Good luck mate!