The following steps apply to Apple Mail. Similar steps can be used for iPhone or iPad Mail Clients.

go to Settings

Then, select Internet Accounts

On the right side, scroll to the bottom and select “Add account”

From the pop-up, scroll to and select “Add Other Account”

The pop-up will refresh, then select “Mail account”

Then fill in the fields for email address (e.g. info@vcfcpro.com) and password (default or preferred password if already changed from RoundCube)
Then click “Sign in”

You will get an “error”, and the prompts will change…
Sign in = email address (e.g. info@vcfcpro.com)
Password = default or preferred password
Account Type = IMAP
Incoming Mail Server = mail.vcfcpro.com
Outgoing Mail Server = mail.vcfcpro.com
Then click “Sign in”

The information will be verified…
If all goes well, a confirmation pop-up is displayed.
Click “Done”
If not, you are given an opportunity to edit the email address, password, and server names.
(The step before this one.)

Optionally, click “Details”

Edit/change the prompts as needed (e.g. Description – this is the title displayed when using the Apple Mail App), then click “OK”

Click the back button to return to Internet Accounts screen.

Confirm the Email Account has been added to the list of Internet Accounts…

Open the Apple Mail App… and confirm that mail account is working…