This message means there’s no information about options, which is required to create a Magento order. For example, a Magento Configurable Product was listed on eBay ignoring variations (as a Simple one). eBay order does not have required options and Magento fails to create an order for the item.
Another reason can be the changed option label. For example, the Configurable Product had the option with the name “Color” and was listed on eBay under this name. Later, the name was changed to “Item Color”, so the names of options (variations) on eBay and in Magento are different.
To create an order, you should set up the options. Go to eBay > Sales in M2E Pro for M1 or eBay Integration > Sales > Orders in M2E Pro for M2. Click on the eBay order ID to open the Order Details page and use the Set Options functionality.
Note: Once you perform manual linking for an option, M2E Pro remembers your choices and all the future orders for this option will be created automatically.