...
If a customer do not proceed while in the signing moment - or when starting to provide card data to external providers, end never returns to the store again, to fulfill an order no traces will neither become available. Therefore, the plugin also logs the moment when customers are leaving your store to sign or use another payment provider to complete the process. When customer returns to the landingpage for success, we again log the landing moment. By doing this, we can keep track of a potential customer that has not completed the order. Order statuses are also marked with those actions so logs don't have to be the first necessary step in troubleshooting.
Step 0: First time running should be a dedicated test environment
If you are entirely new to this plugin, I'd suggest you to run it in a dedicated test environment that is supposedly equals to a production environment when you install the plugin AFTER testing. Primary newly detected errors should be discovered in TEST rather than production. If something fails in production it also means that YOU are the one that potentially looses traffic to your site.
Step 1: Consult the logs
The first step as mentioned here, unless the errors are displayed instantly on screen is to simply consult the logs. Most of the errors, both critical and less critical errors are logged here.
...