Here are common ways to troubleshoot access issues:
Option 1: Send invitation to Owners
-In this case, maybe you forgot to send an invitation to Owners which means they cannot have password to access. All you have to do is choosing the property of that owner, select "Owner" tab, then click on "Invite Owner to claim Owner account". They will get an email with password to login.
Option 2: Resend invitation to Owners
-You can click "Remove property access from this owner" then fill in all information and press "Invite Owner to claim Owner account" again.
Option 3: Reset the password
-If the above solutions does not work neither, the possibility is the owner has already registered his account. What they need to do is retrieving their password by entering their email address at: https://platform.hostfully.com/lostpassword.jsp