A failure to render is probably because the files requested to render are in use in another project, possibly the Main Collection Name Project.
A recommended best practice is to create a new render directory to avoid overwriting the original downloaded rendered files.
Before rendering, or if using ReaWwise clicking Transfer to Wwise, in the Reaper Render to File dialog, specify an Output Directory: with a different name than the original default Rendered directory. For example Rendered_MyProjectName_01. You can keep multiple variations of renders by incrementing the directory name, for example, Rendered_MyProjectName_02.