There are 18 steps in this tutorial but it shouldn't take longer to 4 minutes to connect the 2 systems together.

Steps 1-4

Step 1 - Login into your PromoSoftware account and go to the setting screen.

Step 2 - Click on the Integrations tab.

Step 3 - Triple click in the OAuth 2.0 redirect field to highlight the field, then copy the URL by using CMD or Ctrl + C

Step 4 - Click the link under the fields called Click Here To Go Your Xero Apps Page to visit the Xero apps login page

Step 5

Step 5 - Log into your Xero Apps account using your normal Xero details.

Steps 6 - 7

Step 6 - Make sure you are in the My Apps area of the Xero developer screen.

Step 7 - Click the New App button.

Steps 8 - 12

Step 8 - In the App Name field enter PromoSoftware (if you're using PromoSoftware) or SpinLessPlates (if you're using SpinLessPlates).

Step 9 - In the Company or Application URL enter PromoSoftware or Spinlesspates login URL BUT please rewrite the start to use https e.g. https://test123.spinlessplates.com

Step 10 - Past the OAuth URL that you copied in Step 3 into the OAuth 2.0 redirect URI field.

Step 11 - Tick the T&Cs box if you agree with them.

Step 12 - Press the Create App button.

Steps 13-15

Step 13 - Copy the Client ID by pressing the Copy key to the right hand side. Go back to your PromoSoftware / Spinlessplates screen and paste this into your Xero API Key field.

Step 14 - Press the Generate a Secret blue text to create an API secret code. Press the Copy key to the right hand side. Go back to your PromoSoftware / Spinlessplates screen and past this into your Xero API secret field.

Step 15 - Press the Save button.

Steps 16-17

Step 16 - Press the Save Credentials button.

Step 17 - Press the Connect to Xero button.

Steps 18

Step 18 - From the Xero pop up window, press the Allow Access button to link the 2 systems.