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I checked the website and can see that it's using X Theme 5.2.5 and Cornerstone 1.2.4. I also checked the licence manager and can see that https://walkthru360.com/ URL is assigned to a Pro Theme purchase code. Please note that in this case wherein on website you have X Theme but the purchase code is Pro Theme, validation won't work.
Please convert the website theme from X Theme to Pro Theme by following the instructions from below document.
Once you have upgraded, please refer to the validation guide to validate: