To log in to the PC version of LINE using an email address, you must first register an email address on the device that you normally use LINE on.
See here for the steps to register an email address.
After registering your email address, please try the steps below.
Note: If you haven't already installed the PC version of LINE, you can download it here.
1. Start the PC version of LINE.
2. Click Email Login.
3. Enter your registered email address and password, then choose Login.