What?? Yes, it’s possible!
You can log into Google services like Google Drive or Google Photos with your existing your.name@your-business.com or your.name@gmx.de email address.
Some context: A Google Account and a gmail address are not the same thing. A Google Account is required to log into Google services such as gmail, google drive, youtube, etc. Login with Google even lets you use your Google Account (instead of a username and password) to log into third-party services that support it.
Note: When you create a gmail address a Google Account is automagically created with it.
Google lets you create a Google Account for any email address, specifically for your work address.
Why does it matter?
Other people might want to add you to Google services. If you don’t have a Google Account on your work address, these people will see this error, here is an example from Google Analytics:

It’s recommended to use your official work address for Google (and other) services you use for work, instead of your private (or secondary) gmail address. This way, system administrators can identify individuals when looking at a list of authorized users which increases security for everybody at your company. Nobody knows who frank_82@gmail.com is, but everybody can recognize frank.mueller@yourcompany.com.
How? Here is how to create a Google Account with your non-gmail email address:
- Go to https://accounts.google.com/signup/
- Click on Use my current email address instead
- Enter your official work email address
- Finalize the registration providing the required information

If Google complains that there is already a Google Account for this email address, then please click on Sign in instead and sign in, use the Forgot password? link to recover your password if necessary.
Now your work email address (respectively the Google Account attached to it) can be used by other people to add you to Google Services, for example Google Analytics.