You put it into the game's root directory (where the .exe file is). If you had installed it previously, you have to remove all of its files and install it again - otherwise it won't "see" plugin for Sugoi (which connects xunity translator with sugoi). Btw. as far as I know you can use any version of Xunity translator you wish, which includes reipatcher and melon loader. The important part is to have sugoi plugin in Translators folder after installing Xunity (but before launching the game) so they can "connect" with each other. After that, you just have specify path to Sugoi in the config file and specify that you want Sugoi to translate the the game instead of google (steps 16-18 of the guide). Config file looks the same no matter which version of XUnity translator you are using, be it Reipatcher, Melon or BepInEx.