I faced this issue and fixed it.
the first thing, you need to check everything working or not.
- In the windows Services: SolidWorks SolidNetWork License Manager is running.
- Check file config SWManage.swmc: SWM license server = success!
- Open SNL manager and check license are generated or not.
If the 3 things above are ok but you still get "failed to get a license". please check again the serial key of SNL (It should start with 0016 ....)
I suffer from same issue when I log in SWM-Web client. Install version of SWM works well.....
Is there anybody who solved this problem?