I have set up federation to lastpass for business with Azure AD, the provisioning seemed to work as expected and I can see my test user in the list of federated users. So logging in as this user I can see the email inviting me to activate the LastPass account, however when I click the link I am directed to the Reset Master Password page and simply can't get past this, according to the documentation for the new user experience I should be directed to the page where the activation code can be entered but I never see this page, whats going on?
Could you try opening the invite link in the email in a different browser, or try making sure all popup/ad/content blockers are disabled in the browser and opening the invite link again? What happens exactly after trying to set/reset the master password?
If you'd like assistance right away we would recommend contacting the Business support team by phone any time, you can access the support number through your LastPass Admin Console > Support or request a callback by scrolling down and clicking "Contact Support" on this page and entering your Business account info and you should then be given the option to receive a callback usually within less than 5 minutes: https://support.logmeininc.com/lastpass/help/how-do-i-contact-customer-support-for-lastpass-lp010121
This does now work as expected for Chrome and Edge browsers but am still seeing the issue for Firefox (my default), popups are allowed and the extension is installed so not sure why I'm seeing this behavior. We'll continue using Chrome/Edge for the time being