To download and install the official 64-bit version of reFX Nexus 2 , you should use the reFX Cloud app provided by the manufacturer. Official Download & Installation
DAW Not Seeing Plugin: Advise readers to ensure the Nexus2.dll is located in the correct 64-bit VST folder (typically C:\Program Files\VSTPlugins) and that their DAW's plugin manager is set to scan that specific path. refx nexus 2 dll 64 bit link
Note on Nexus 3 & 4: ReFX has officially discontinued Nexus 2. The current versions (Nexus 3 and Nexus 4) are native 64-bit plugins. If you own a legitimate license, your best "link" is the reFX Cloud app, which automatically installs the correct 64-bit VST/AU versions for your system. How to Get Nexus 2 Working in a 64-bit DAW To download and install the official 64-bit version
Newer versions (Nexus 3, 4, and 5) use online activation and do require the physical USB-eLicenser. 3. Troubleshooting & 64-Bit Bridging Reinstall the plugin : Try reinstalling Refx Nexus