Still, try the following way to resolve this Microsoft office 365/2021/2019 installation error 30068-4, If you see an error that contains Error Code 30068-4 when you try to install Microsoft 365/2019 and 2021. And in some cases, the installation or update of Office may end up with installation Error Code 30068-4 (1715).
Temporarily disable windows defender and Antivirus
While installing or updating the Microsoft Office may do installation Error 30068-4 or Error 30068-4 (1715), due to restriction in Network or firewall. The rules set in network rules or firewall in the computer may block the installation of Office program or its updating as a part of their security measures.

By disabling or giving expectation in the windows defender or Antivirus, you could fix the office 365/2019 Error Code 30068-4 (1715) for Microsoft Office 365/2021/2019 Installation or update.

https://www.unlicensedproduct.com/office-installation-error-code-30068-4-and-error-30068-4-1715/