TexGen is a tool which updates a select list of object LOD textures and tree/grass LOD billboards for which are then used by DynDOLOD to create the final object LOD and tree LOD texture atlasses.
Found stitched object LOD textures from earlier TexGen generation
TexGen checks if there is TexGen output already installed in the load order. It should be removed before generating stitched object LOD textures for the current load order.
In case TexGen output is to be included in a mod, set CreateMode=1 in ..\DynDOLOD\Edit Scripts\DynDOLOD\TexGen_[GAME MODE].INI as explained in Mod Authors.
Detected LOD textures from an older TexGen version
Uninstall the outdated TexGen output and run TexGen to generate updated object LOD textures and tree/grass billboards for the current load order.
No TexGen output detected
The message means that the TexGen output is not installed, incomplete or access to the data folder to check for the output is prevented by the OS, anti vir or 3rd party software.
Run TexGen before DynDOLOD to update a select list of object LOD textures and tree/grass LOD billboards to match the current load order.
Make sure TexGen completed the generation object LOD texture and tree/grass LOD billboards successfully.
The output from TexGen should never be overwritten by anything.
Ignoring the message is not recommended for best visuals and performance.