[Syzygy1]

There isn't a SA-MP 0.3.7-R2 client. You can connect to R2 servers with the standard 0.3.7 client; the R2 update was for server owners only, as you can read here: https://sampforum.blast.hk/showthread.php?tid=581259

However, if you're talking about the R2 server package, the download link works fine for me, that is, it downloads the R2 package.