If you ever suffered the pain of someone not being able to share Google Drive files with you because you didn’t have a Gmail account or they didn’t know it. You can create your own Google Account (like the Google identity) but using your own current email account 😉
You will also be able to use all the Google Drive functionalities (Docs, Sheets, etc.) and you will be able to share and receive shares from other Google users. Just ask them to share the document with your existing email account once you opened your account.
To create your Google Account Identity follow the below instructions:
1 – Click on the below link to start the creation of your own Google Account:
2 – Once the page opens, click on the “Use my current email address instead” option:
3 – Complete all the details as shown below and click on “Next”.
4 – You will receive an email with a verification code on your entered email account, you will need to use this code on the following screen, once entered click on “Verify”.
5 – On the following step you will be requested to enter a mobile phone number (optional), your birth date details and your gender. These details will help you recover access to your account in case you forget your password.
Note: If you enter your mobile phone number on the following step you will be asked if you want to verify it, we recommend you do this, an SMS will be sent to your mobile with a code which then you have to enter it on the screen to continue the setup of your Google Account. 
6 – On the following screen you will be asked to accept the privacy and terms. Once you are ready click on the two check-boxes at the bottom of the screen (you need to scroll down) and click on the “Create Account” button.
7 – Re-confirm your account creation by clicking “Confirm” on the following screen:
8 – Once your account has been successfully created, you will be displayed your “My Account” home screen, which looks like this:
Once your account has been created you can let your colleagues or firends that they can start sharing Google Drive documents with the email account they already knowas it has been associated with a Google account.
To access files shared with you over Google Drive, go to https://drive.google.com to access them.
You will also be able to create Google Drive Docs, Sheets, Slides and more with your new Google Account, to learn about more things you can do, check the following link: https://support.google.com/drive/?hl=en#topic=14940
To change any details or if you need to login to your Google Account you can do so by entering to the following link: https://myaccount.google.com
Note: Remember that your username is your own email address you have chosen to create your account.
If you need additional help on the Google Account creation options you can check the below Google Help article:
https://support.google.com/accounts/answer/176347?co=GENIE.Platform%3DDesktop&hl=en