Try the Microsoft free inbuilt Exmerge.exe utility to convert EDB to PST. Below I share the manual steps of Exmerge.exe utility.
1. Install the Exmerge.exe utility. Open the utility and log in Exchange Server.
2. In the Microsoft Exchange Mailboxes Merge wizard and click on Next.
3. In the Microsoft Exchange Mailbox Merge Wizard select the Two Steps Procedure and click on Next.
4. Click on Extract or Import option and click OK.
5. In two step procedure, select Extract data from an Exchange Server mailbox and click Next.
6. In the Data Selection Criteria, now click on Import Procedure and Archive data to target store. Click OK.
7. Now, click on Message Details and fill the information and click OK.
8. Now, select the mailboxes which you want to export and click Next.
9. Choose the location to save PST files and click on Next.
10. Final Click on Finish.