If you get stuck with your Linkedin validation, you should visit your Linkedin account by just doing a quick check.
If everything seems as usual then turn back to Salesloop, refresh the app and try to revalidate your Linkedin account.
If you have a security check from LinkedIn, just solve the puzzle and show you are a real person. When you login LI, turn back to Salesloop and revalidate your account. That will solve your stuck.