Hi memoryman18,
In fact, what really puzzles me is why, in 2024, your mother would choose to buy a tablet from seven or eight years ago, which makes me have to consider whether the merchant is dealing with inventory of unsalable items or whether some dishonest selling is involved.
I checked the github link you provided, it is not supposed to be the official driver download address, it looks like an enthusiastic user spontaneously organized and uploaded to github 8 years ago.
While I tend to believe that the github driver might be available, there doesn't seem to be an audio driver in the directory. Or maybe I don't know how the driver should be deployed on your computer (since it doesn't appear to be an exe application that can be installed directly) because it's not a Microsoft product.
I still think that if you want an official driver, you should contact the seller of the device, because the seller usually works with the manufacturer of the device, and they should share the driver information so that the seller can provide it to the consumer.
The second link you provide is also an unofficial source, which may cause errors if you download and install the Intel SST Audio Device (WDM) driver. Because the device model does not match, unless you can find a solution to confirm that the model driver is suitable for your tablet, but the problem is that we can not confirm this, only the official support of Trekstor can confirm this.
The third link is to the Microsoft Update Catalog site, and although this is indeed a Microsoft site, you are still searching by "Intel SST Audio Device (WDM)" and it is difficult to confirm that the drivers you download here are suitable for your tablet device.
In response to the need to downgrade Windows that you mentioned here, from an official point of view, unfortunately, there is no way, because Microsoft officially does not have older versions of Windows to download and install. If Trekstor has dropped support for this type of device, and we are unable to provide you with an older version of the system through official channels, and we are unable to downgrade the current version of the system, perhaps I can only suggest that you find some user-made older version installation media online and try to use them to reinstall your system.
But if this is a new tablet, perhaps you can negotiate a return or exchange with the merchant? As long as your device is within a refundable period.
Alternatively, I might be able to suggest that you try resetting the device back to factory Settings and perhaps the audio driver issue can be resolved:
Recovery options in Windows - Microsoft Support
To prevent data loss, back up data in advance.
But let me emphasize again that if you want to get a driver or system media for the device model, the only correct source is still to try to contact Trekstor, unless they have explicitly stated that the device model is no longer supported.
Best regards,
Mitchell - | Microsoft community support expert from MSFT