Problem Azure lab register

U1142836usqeduau, 

Since there was no error message included in your post, let me give you a few things to check.

1. Verify you are using the same email address that the register link was sent to.
2. Make sure you are using a Microsoft Account or Azure Active Directory account. 
3. (See How to access a lab in Azure Lab Services - Azure Lab Services | Microsoft Docs for explanation.)  If you are using gmail account, make sure to tie it to Microsoft Account.   If you haven't, go to Microsoft account | Sign In or Create Your Account Today – Microsoft to create a new account.  Enter your Gmail account email address when prompted for an email address.

If neither of the above help, you'll need to contact your lab administrator.  They will need to check their lab user list and possible lab restriction settings.  They might need the register code sent to you to find the lab you are assigned to.