Seems you missed some key text at the top of the Report an Issue form.
Report An Issue is intended for Reporting Possible Software bugs. Questions on how to work with FileMaker Pro should be posted in the FM Pro Forum Section. (See tab at top of this screen.)
A Post made there will be seen by and responded to by a lot more users than you will get from a post made here where people expect to see reports of possible bugs.
That said, from what you post, there seems to be some confusion here over "templates" and "layouts".
When you select New Layout while in layout mode, you can specify that the new layout be a labels layout and if your desired Avery number is listed, you can then specify the Avery Number before selecting the fields you want to supply data to each such label printed.
Note that this creates a brand new layout. If you perform a find on this layout for the records where Send Card is 1, you should then be able to print a single label for each such record. I strongly suggest, however, that you enter preview mode and double check your results before printing from a labels layout. With some printer-avery Label combinations, the last row of labels won't be printed--the data for them gets printed on the first row of the next page--until you "tweak" the dimensions of your layout parts slightly in order to get it all to print like you want without wasting a row of labels on each page.