The Post Office Protocol version 3 (POP3) is a standard mail protocol used only to receive emails from a remote server. As such, it will have no record of emails that you have sent and it has no concept of folders; everything is a flat list of mails (unlike importing using the IMAP protocol or from an Outlook PST data file, which do support sent items and folders structures).
If you configured a version of Outlook installed on your computer then you likely have all of the details that are required:
Port (nearly always 995)
Email Address of the account to retrieve mails for
Password for that account (see notes further down about this)
If not, then you should be able to get them from your mail provider.
One common examples is Gmail:
Click the "settings" cog near the top right of the screen and then See all settings
Click Forwarding and POP/IMAP
In the POP download section, click Enable POP for all mail
Ensure that the When messages are access with POP that the drop down has the selection keep Gmail's copy in the Inbox (this is so that a copy of the emails are imported into Curiosity while still being accessible through Gmail (or whatever software you use to read these mails)
Click Save Changes
Click on Configuration instructions in the POP download section and you will be taken to a page that shows the Incoming Mail (POP) Server with the host that you require and confirmation of the port number
The Email Address that you will enter into the Curiosity connector configuration screen will be the email address of your Gmail account
The Password may be the password that you use to log into your Gmail account online or, if 2-Step Verification is enabled, then you will need to configure an App Password as described in the Google support document "Sign in with App Passwords"
Another common example is Hotmail / Outlook.com:
Click the "settings" cog near the top right of the screen and then View all Outlook settings
Click Sync email
In the POP and IMAP section, ensure that Let devices and apps use POP is set to Yes (if it is set to No and it is disabled then you may need to talk to your email administrator to enable you to change this—this is more common when Outlook.com is used for company mail and your email administrator in this instance will likely be someone within your company and not Microsoft)
Under POP setting, there be a server name value, which is the host that is required to configure the connector and it will show the port
Creating a POP3 Connector in Curiosity
Click the menu button at the top right of the Curiosity application, then Connect Sources, then POP3 Mailbox. Within the popup that appears, click + Add.
You may wish to change the Name of the connector to relate to the account that you are importing (eg. Dan @ Curiosity POP3 Task), likewise for the Source (which will make it easier to filter email results based upon which connector, and so which email account, the mails came from).
Enter the Host (aka. Server Name) value
Change the Port if 995 is not the appropriate value (which is unusual)
Enter the Email Address
Enter the Password
The default schedule (as specified by the Cron value) is to run the import at 1am every night but you can change this (and find out more information about initiating a one-off import manually and viewing the import logs by reading the "Scheduled Tasks" article).
(Warning: Some POP3 providers will reject connections if they are made too often - for example, see the "'Account exceeded POP command or bandwidth limits' error" in the Gmail documentation - this is highly unlike to occur if the schedule is less than every hour and almost impossible if it remains at the default frequency of once a night)
Unless you change the Permissions settings, all imported emails will be visible to every User of the Curiosity system. To change this, click on the Edit button alongside the Permissions label:
To change the import from making all emails imported by the connector accessible to everyone, change the toggle from Public Access to Restricted Access. This will reveal a search area where you may select one or more Users and or Team that will be granted access.
If you change your mind and wish to return to importing as public then switch the toggle back to Public Access.
Click Save to close the permissions popup.
If you have selected specific User(s) and / or Team(s) then they will now be listed alongside the Edit button by permissions.
Click Save to complete configuring the connector.
Either wait until the specified schedule that the connector is configured to run at or click the Play button now to import the emails that are currently present in the POP3 mailbox.
Note that some email clients may delete emails from the POP3 account after downloading them and so the entire history may not be available any longer. If this is the case then you may wish to investigate using an IMAP connector or by exporting Outlook data to a PST file and importing the emails from that by using the Curiosity Command Line Interface—also referred to as the "Curiosity.CLI".