Guest Access to SharePoint

Hello All, 

I've added a few guests under 1 site ...as security groups only on that site 

Issue

Then add them directly to the folder they need access to and its contents 

Changed the default sharing option to People with existing access 

Guests need to sign in at least once using MS AUT

All working fine 

Question  

Is there a way to allow those guests to access using people with existing option

Without signing in? 

Best Regards 

Anis