Hi zoryana226,
We see you're attempting to sync your iPhone to your Surface Pro 7, however when dragging and dropping it doesn't work.
iPHone can be synced with one computer at a time. If you'd like to no longer sync with this other computer and instead sync with your Microsoft Surface, you can choose to erase and sync to start syncing to your new device. The excerpt from the following article clarifies further: Use iTunes to sync your iPhone, iPad, or iPod with your computer
"You can only sync your device with one iTunes library at a time. If you see a message that your device is synced with another iTunes library, your device was previously connected to another computer. If you click "Erase and Sync" in that message, all content of the selected type on your device will be erased and replaced with content from this computer."
Let us know if you have any other questions.
Take care.