Step 1
Navigate to https://console.cloud.google.com/ and select an existing project or create a new one
At the top of the screen, search for Analytics API
Enable the API
Step 2
On the same Google Analytics API page, go to Credentials
Click the Create Credentials button, and then from the menu, select API key
Step 3
On the same Google Analytics API page, go to the OAuth consent screen
Fill in the App name, User support email, and Developer contact information fields
Click the Save and continue button until the last page, Summary, without changing anything on Scopes and Optional info subpages
Step 4
Click the Create Credentials button, and then from the menu, select OAuth client ID
Select Web Application, enter Name and paste the Authorized redirect URIs from your MainWP Dashboard > Extensions > Google Analytics > Add Account page, and click the Create button
Step 5
On the Credentials page, click Click Download OAuth client to your computer for later
Step 6
Click the OAuth consent screen, then click Publish App button & click Confirm Button
Step 7

Locate the Credentials you saved to your computer & open them in a text editor of your choice.

Navigate to MainWP > Extensions > Google Analytics > Add Account

Enter your Credentials & click Connect Account

Note: ( PROJECT ID = ACCOUNT NAME )
Step 8

Select Your Google Analytics Account

Click Continue to give consent to your MainWP Dashboard

Click Advanced on the SSL Warning ( don’t worry about this – you’re ok )

Click Goto Unsafe Website.

Done: Please check the Manage Accounts tab to verify a successful connection

Important Notes: 
If the process keeps failing for you, please try a different browser and ensure that any ad-blocker add-ons in your browser are disabled.