Importing pst into new exchange database

Please refer this article on how to import pst:
https://practical365.com/exchange-server/exchange-2010-import-pst-files-mailboxes/

Have you looked at the articles on this site?  Specifically https://www.experts-exchange.com/articles/32087/Importing-PST-Files-into-Microsoft-Exchange-2016.html - the process should be essentially the same if I remember correctly.

OK did the third party tool export the mailboxes with the users alias name? If not you may need to rename them. then I've put instructions and a video here;
Exchange: Importing Mail From PST Files (including Bulk Importing)

Regards

Pete

I think you can just add it to the outlook profile, then right click on the top year of the pst, then copy to, exchange.ost thing

You can import Mailboxes directly to new database by using New-MailboxImportRequest command. This command is compatible with Exchange Server 2010, Exchange Server 2013, Exchange Server 2016, Exchange Server 2019,  You can check full steps from here: https://docs.microsoft.com/en-us/powershell/module/exchange/mailboxes/new-mailboximportrequest?view=exchange-ps