Steps :
1) Adding Webgility Integration On Magento 2:
First of all, you need to enable OAUTH in Magento 2, for that we need to go to
Stores → Configurations → Services → Consumer Settings → OAUTH → Yes → Save.
2). Go to System> Integrations
3). Add a new integration by clicking Add New Integration.
4). Name the Integration. Type in your store login email address and password.
5). Provide All resource access to the API, by selecting from the dropdown menu under Available APIs.
6). Activate the new Webgility integration by selecting Activate.
7). Copy the Store URL and paste it into a notepad as shown in the screenshot below.
8). Copy the Access Token and paste it into a notepad as shown in the screenshot below.
Connecting with Webgility:
1). If this is the first time you are adding Magento 2 as a new store please follow the steps as shown in the screenshot below:
2). In the next steps, connect QuickBooks Online with Webgility. Follow the steps as shown in the screenshot below:
Next, here is the list of the documents that you can explore to set up your Magento 2> Webgility Online> QuickBooks Online integration.