How do I fix the problem of checkout page not loading on my website?

my website is having an issue, I can't seem to pass the checkout page. I have tried making a test order but when I click on 'place order' it just loads and the page does not refresh making it impossible to make an order. I don't know if it's a problem with my CMS or maybe the theme or maybe the case of a plugin. Please can you help me out?

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