Step 1
Check if username (your gmail id) and password are correct and you are able to login on https://www.google.com/gmail/
Step 2
If Step 1 is okay, then try to open Less secure app access setting and turn this to OFF
- https://myaccount.google.com/lesssecureapps (In case your email is personal account)
- If your email is created by Google Admin (Gsuite), then you need to contact your Administrator and ask then to turn this setting to OFF for your account
- Sign in to your Google Admin console
- From the Admin console Home page, go to Security > Less secure apps.
- To apply the setting to everyone, leave the top organizational unit selected. Otherwise, select a child organizational unit or a configuration group
- Select the setting for less secure apps: Allow users to manage their access to less secure apps.
- Click Save.