I wanted to start this by saying that this process is a nightmare. Really it isn’t a nightmare when you understand it. The problem is that this product’s configuration setting to set up a new computer to use an old computer’s .pst or .ost file is so confusing and the online explanations are so convoluted that a non-technical user may never figure it out.
The key to understanding this is when you set up the account, the initial account (on the new computer during the first set up of Outlook), you need to do a couple of things. First, you have to set up using the manual options. The automatic options work but the assumptions that Microsoft makes is just garbage. If a server uses imap and you don’t know what that is and your old set up used POP you could waste a great deal of time trying to figure it out.
Check your old install if you can. You are looking for whether your old server uses POP or IMAP. Consider IMAP a command to make both the computer and the email server equal as far as messages/folders, etc go. POP allows you to download the email from the file server for local storage where you can optionally delete the emals from the file server. Make sure you understand this.
If you have a server with only a small amount of space to keep your email you will need POP instead of IMAP. This allows you to grab the email and and delete it from the server. It is up to you though to ensure you have a backup of the local mail store. In Outlook the local mail store is the <filename>.pst/.ost file. Note: For the least headache this should be backed up on a regular schedule.
The problem that is of major concern in setting up the new computer to use the old .pst or .ost file is that you need to ensure that when you copy over the .pst and/or .ost file you note where that file “is needed” and “where you put it”.
When you start the initial setup of Outlook you need to choose the manual option, and tell it that you want to use an old/existing data file (instead of creating a new one). You will need to browse to the file and select it. Once selected to use an old file and you complete the setup your old file should then become the primary data file associated with the new account. If you just add the data file to a new account (say after doing the automatic setup) this file will just be added data. All new mail won’t enter that file, it will be in the new .ost file instead. This is very confusing to a non-technical user.