...
Check the SAM service is running (via Services, check Snare Agent manager is started)
Check the tcp port is open? Execute netstat -na | find "6261" You should see a TCP connection on 6261 there.
Check the minimum browser requirements:
Windows - Internet Explore 9+,Chrome (latest),Firefox (latest)
OSX - Safari (latest),Chrome (latest),Firefox (latest)
iPad - Safari (latest)
If you are using Microsoft Edge see the Knowledge Base article for further information Using Snare Windows agents on systems with Microsoft Edge browser.