It may be necessary to select Manage Library manually since it may not appear automatically. If that doesn't work, I would try replacing the cable, using a different USB port and a PC running Windows 7.
If an Unknown Device appears in Device Manager when the Kobo is plugged in, there may be an issue with Windows recognizing the Kobo. Not sure if it is applicable but it may be necessary to set Windows to automatically download drivers or manually find and download a Windows driver for the Kobo.
If not already done, a reset may help.
Resetting your Kobo Glo HD
Here is a link to the User Manual
Unfortunately, many companies stop supporting devices after a few years or when new versions of operating systems are released. (I've had this happen with lots of hardware.) It might be possible to find an unofficial workaround to make it work with Windows 10 but it would be a long shot.
If an Unknown Device appears in Device Manager when the Kobo is plugged in, there may be an issue with Windows recognizing the Kobo. Not sure if it is applicable but it may be necessary to set Windows to automatically download drivers or manually find and download a Windows driver for the Kobo.
If not already done, a reset may help.
Resetting your Kobo Glo HD
Here is a link to the User Manual
Unfortunately, many companies stop supporting devices after a few years or when new versions of operating systems are released. (I've had this happen with lots of hardware.) It might be possible to find an unofficial workaround to make it work with Windows 10 but it would be a long shot.