People with retail versions of Windows who received the free Win10 upgrade use the Win7/8/8.1 activation code. I've had issues with those when hardware was upgraded. People buying retail copies of Win10 may have received a new activation code. Not sure because all my licenses are retail upgrades. Others received a license tied to an Outlook email account. I find the Outlook email method to be more reliable. Just create an account at Outlook.com. Then go to Start > Settings > Activation > Add a Microsoft Account and register it. Windows will now use the email account for activation and login. It can be changed back to a local login but the email account can be used to activate Windows 10 when needed.
It's possible that this particular drive just won't work with that laptop. They should be compatible but it's never 100% guaranteed. Chances are the laptop wasn't designed with SSDs in mind or there could be some oddball SATA chip inside it.
My reason for recommending a 250GB drive is partly due to Win10's tendency to increase in size with time. Every update makes Win10 grow by at least the size of the update and that's just the start. Win10 can double in size in a couple of years and there is no easy way to get rid of it other than a fresh install. A 120GB SSD drive may be good enough for Win7, I've installed it on a 60GB drive, but Win10 is less forgiving. 120GB should be OK when few personal files are present. Another consideration is that larger SSDs are faster and will typically last longer.