Zoho Desk > Account creation

Zoho Desk > Account creation

Hey there, 
we've been experiencing some random problems when our clients want to create an account on desk. 
When we accept a user, they receive a link to set up their password but often times, they are blocked either with "enable cookies" (already enabled) or "something went wrong, try again later" . Seems to be random and changing browser has no impact. 
It starts to be an issue for us since clients can't access ticketing and help center. 

Any idea ?