We are currently using outlook (domains.live.com) as our email provider and are in the process of procurement of an in-house mail server. Please guide me in the process of migration to Exchange 2013 for around 200 users.  If outlook is configured on POP3, then the PST files have only inbox data. Outlook connector creates OST files which cannot be copied, but only these files have complete data with the folder structure. How can I migrate the data from OST files to Exchange 2013, or is there is any other way for us to go with this? 

You can move the OST files to PSTs, then connect the PSTs to an Exchange 2013 profile, and copy the PST contents into the mailbox.  There's an import feature in Outlook that can do this.

You might want to consider a third-party tool like MigrationWiz, especially if you have a lot of mailboxes.

https://www.migrationwiz.com/Public/Solution/HowItWorks.aspx