You can use Gmail and Grammarly altogether and do so-
• You have to install the Chrome extension
• Now, go to the Chrome Store and search Grammarly
• Choose Grammarly and download it and click on Add to Chrome
• You will be then redirected to a welcome page and there you can go to Gmail automatically from the site and then compose a new email
• A new Compose window will be then appeared
Now you can check if you have integrated Gmail and Grammarly and if it is not working then, Gmail Help Care Number UK to get connected with the technical experts.