Hey, I know we are in 2021 and most likely not much users are doing this challenge at the moment. This is my solution, looking forward to keep learning with the challenges, with this one I learned about the generate rows tool.
Data Types are always important: When you split the range to start and end - ensure the fields are numeric
Generate Rows: You obviously didn't know about this tool when you started with Alteryx but this is one of the only tools that gives more records as output than input, I have shared the config in spoiler
other examples is Text to Columns, yes, surprisingly it has an option to do Text to Rows too; Alteryx 1 Excel 0