In your output panel, it is clear that the first line of your captured text block is “Vendor Information”. So, when you split this text with new line, the first element in the array will be “Vendor Information”. Then you try to split this text with a delimiter “:”, and capture the array element 1, it will return an error because that index doesn’t exist.
You can either solve this issue by start splitting “VendorinformationArray” from the first element, that is,
out_TaxID = VendorInformationArray(1).Split(":"c)(1).Substring(1) or in the get text activity, select the text block excluding the line “Vendor Information”.
If you are using “.Substring(1)” to remove the whitespace in your split string, you can otherwise use “trim” method, like out_TaxID = VendorInformationArray(0).Split(":"c)(1).Trim