How to Link Excel File with Outlook for Popup Reminder

I think there is a logical error in your design. (A) If the date is in Excel, Excel can take action when the workbook is opened on that date but not if it remains closed. The action could be to send a mail or to make an entry in Outlook's calendar. (B) If the date is in Outlook (perhaps because Excel put it there) Outlook can take action on that date. However, I believe Outlook's capabilities when closed are limited. It may (or may not) beable to send an email, but it would likely need to be opened in order to show a popup (message).
Therefore,

1. if the action you want is to show a message, this message should be shown by Excel, and it can only be shown when the workbook is opened. No need for Outlook.
2. if you want an action by Outlook you should first transfer the dates from Excel to Outlook's calendar. This should be done when the workbook is opened, irrespective of date.
   1. Once the Outlook calendar has the date, Outlook can be programmed to show a message when it is opened on that date.
   2. However, it's probably superfluous to show a message. Instead the program should execute the action which the message is supposed to remind of. For example, instead of "send a message" - end, "do you want to send a message?" - and send the message if yes.

To realise any of this programming you should show some own effort. Take a look at the posts of the last few days here on the forum. There is code how to open Outlook from Excel and send a message.

Excel can add a reminder or a recurring one for some interval to Outlook.  As noted, Outlook needs to be open to get that popup.  I guess you will need a column to show recurring or not.  I would also add a column for a boolean True or False if it was set.  Any values not True in that column would get set to True after the Excel macro was ran.

This has code and explains recurring appointments.:

https://docs.microsoft.com/en-us/office/vba/api/outlook.appointmentitem.getrecurrencepattern

If you want to set Outlook to put the popup reminders on top of other windows:

https://support.office.com/en-us/article/set-or-remove-reminders-7a992377-ca93-4ddd-a711-851ef3597925