Richard: Great! You found your Enumeration District - it's actually a two-part number 41-533 with the 41 prefix being for Queens. When you go to https://1950census.archives.gov/ you can type in your search for New York / Queens County / ED 41-533 If you add in the name Riggs, you are correct, it is not returning any results.
The name index is not yet perfect. Searches for the name of the head of household often work best – because the census takers wrote the surname only on the line for the head of household (usually male) and other people in the household with a different surname. In addition, the draft 1950 census index was created using machine learning assisted Optical Character Recognition (OCR), which can be inaccurate due to issues such as: illegible handwriting, poor image orientation (slightly sideways), variations in image quality (light, dark, or poor contrast), text obscured by handwritten flourishes from letters on the line above or below, different handwriting styles, and because surnames written only on the line for the head of household and other persons in the household with a different surname. For more information see https://historyhub.history.gov/community/genealogy/census-records/blog/2022/03/18/1950-census-please-help-nara-refine-the-draft-name-index
Alternatively you can read each of the 36 pages in Enumeration District 41-533 - it might be fun! Here's a direct link to the Enumeration District: https://1950census.archives.gov/search/?county=Queens&ed=41-533&page=1&state=NY. Click on the blue box that says "population schedules" to get started.