If you have purchased an eSIM and you are having issues scanning your QR code, you can manually enter your eSIM details in your handset. You need however to get some details from your eSIM provider.
Esim.travel gives great information about how to manually add an eSIM to your device
If you cannot scan the provided QR Code, you can install the Travel eSIM by entering details manually.
You will be asked to enter the SM-DP+ Address, Activation Code, and Confirmation Code – all of which are included in the United Global eSIM Activation email.