try install through other cia manager like FBI or BigBlueManaager.
you can find full tutorial how to install this tool in here
https://gbatemp.net/threads/tutorial-patch-twl_firm-to-play-normally-blocked-ds-games.414578/
excuse me.I still dont get it.can i use just 1 emunand for both rxtool and cakesfw(Just copy all the files to the root of SD card, and launch? ) or i have to make new emunand for cakesfw ?