The issue is that you have a lot of urls which 301 redirect to others, so that the crawling chain is broken.
Usin Xenu I only found these urls:
https://www.captussystems.com/ https://www.captussystems.com/cdn-cgi/l/email-protection https://www.captussystems.com/servicesgroups https://www.captussystems.com/servicesupport https://www.captussystems.com/contact https://www.captussystems.com/pages/about https://www.captussystems.com/blogs https://www.captussystems.com/pages/termsandconditions https://www.captussystems.com/pages/privacypolicy And these other urls that are 301 redirected - and consequently any urls to be found further are not going to be accessible to a crawler like Xenu and like to GsiteCrawler either.
Ensure your internal navigation is free of any redirections. Use the correct final urls at all time.