Hi,

Better solution is to set up the outgoing email server and users will be receiving in the invitation to access the portal, once they try to access initially they will be asked to reset the password. If setting up of outgoing mail server is not possible, to reset the user password, Go to Settings -> Users & Companies -> Users, search and open the invited user and from the action button you can set the password for the user.

Even if this is the case, you have to send the user name and password to customer some how in other ways. So you can consider sending the invitation link in the same way, so that he can set a password.

Once user clicks on corresponding link,

Thanks