This depends on your current media server Windows Operating System Version and if its 32 bit or 64 bit.
You would need or perform a multi Step upgrade.
First upgrade to Backup Exec 2010 R3 then to Backup Exec 16.
How to: Direct upgrade path from Backup Exec 11d/12.0/12.5/2010/2010 R2 for Windows Servers to Backup Exec 2010 R3
https://www.veritas.com/support/en_US/article.100024400
Upgrade checklist for Backup Exec 2010 R3
https://www.veritas.com/support/en_US/doc/59226269-99535599-0/v53887653-99535599
NOTE::
1) You must have access to the Backup Exec 2010 R3 media
2) You need to check the Backup Exec 2010 R3 and Backup Exec 16 SCL to confirm what you are backing up is supported. Many older operating system, SQL versions, etc are no longer supported.
SCL - Backup Exec 2010|2010 R2|2010 R3 Software Compatibility List
https://www.veritas.com/support/en_US/article.100002663
Backup Exec 16 Software Compatibility List (SCL)
https://www.veritas.com/support/en_US/article.100032806
Once you get to Backup Exec 2010 R3 you can then migrate the 2010R3 installation to newer hardware or OS.
Backup Exec 16/20 only support 64 bit media server OS's.
Veritas Backup Exec Migration Assistant
https://www.veritas.com/support/en_US/article.100041264
