This guide is based on an iPhone SE with iOS version 11. Every iOS version may have a slightly different set-up process. In addition you may choose to setup email with an App of your own choosing. If you need assistance with a different device or app please contact your vendor, or Topmail Support. If you only need the server settings information for Topmail you can get that here: Topmail Server Settings.
Click on "Get Started".
Choose your notification preferences.
Click on Skip or if the Topmail account is listed as "found" one, choose it.
Enter your full Topmail email address in the corresponding field and tap on "Add Account"
It will think for a while and redirect you for the manual set up.
Enter your correct Topmail email address and password.
Also, fill in the other fields.
Tap on "Sign In"
If it fails with the signing you in, tap on "Advanced Settings" to enter server settings manually.
Enter the following settings for the IMAP:
Email address and password fields should be filled already as you have entered those data earlier. If not, enter it again.
IMAP Hostname: imap.topmail.com
IMAP Username: your full Topmail address
IMAP Password: your password to the Topmail account
Enter the following settings for the SMTP:
SMTP Hostname: smtp.topmail.com
SMTP Username: your full Topmail address
SMTP Password: your password to the Topmail account
And finally, tap on "Sign In" and it should sign in you to the account.