“Unable to install printer. The print processor does not exist.” error when you attempt to manually add the ThinPrint Output Gateway (TPOG) template. Can also show up in the Windows Print Management console with the “WinPRN processor does not exist” error.
Server OS is likely not recognizing TPOG driver.
See “Solution” below
When manually adding the _#ThinPrint Output Gateway template via the “Add Printer” option, select TP Output Gateway driver and then use the option “Replace the current driver”.