Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
Sidesync has to be installed both on the PC computer, and (in a slightly different form, as an app) on the phone you wish to sync with the PC. Once installed on both, you need to get the communication between the two going, for Sidesync to work.
If you have gotten to the phase where the two devices should connect, but are getting a 'please wait' message and no further progress, it is likely that your PC has security software (a Firewall) that is blocking communications. A crude way to tell, with some dangers, is to go to your Firewall software, turn it Off temporarily for a few minutes, and try the Sidesync connection that way.
(Whether or not disabling the firewall gets the Sidesync connection working or not, you must re-enable your firewall promptly! or your PC may be attacked, disabled, and/or infected from the Internet - or even from relatively nearby, if you are connecting to the phone by wireless of some sort, which I presume you are.)
Let me know more details in Reply - e.g. where you are when you get the 'Please wait' message - and I will advise you specifically according to specifics of your case.