Why can't I log in to a client's store after granted access?

[Jamllizy202]

After my clients grant me access to his store when I sent a request as a collaborator, I am unable to log in and it's bringing 2 option go back to store list and enable two way authentication 

[Ollie]

Hey @Jamllizy202.
 
Thanks for reaching out. 
 
If you are experiencing an issue with an online store regarding collaborator access, I would suggest attempting to  clear the cache on your browser and try to login once again. In some cases, clearing the cache from your browser can fix minor issues that you may experience on the Shopify platform. 

With that being said, if the issue persists - I would suggest attempting to use a separate browser. For example, if you are using Safari - try this action on Google Chrome. 
 
Let me know if that does the trick.