The reason why this changes is that Microsoft does not longer allow driver signing with SHA1 (which is considered to be "broken"). The new certificates (that are also valid for just a limited time) are SHA256 certificates and - like before - the driver must be signed by us and signed by Microsoft, including a timestamp.
So there is no possibility to create new driver packages without the SHA256 way.
Windows 7 did not support SHA256 in the first place, it needs a specific update to support SHA256 for kernel drivers. Usually, this is already installed since 3 years, when auto update is enabled. This is something, I would recommend.
In case users are picky with the updates, they usually deny the update. In this case, the specific update needs to be installed.
You can find more information about this issue here:
After installing this specific update, Windows 7 is able to run Rig Manager 2.3.
I was finally able to update to Rig Manager 2.3.13 and my profiler to Operating System 7.1.0 Public Beta by installing the following patches on my Windows 7 64bit OS (in this order!):
Many thanks to Timo for his support and suggestion that finally got me past this roadblock!