The WinTD Reports—Email/Text Pairings operation depends upon having either an e-mail address or an SMS (Short Message Service) address for a cell phone number. While there are services that will send texts in bulk given just the cell number, they charge for the service. (They aren't prohibitively expensive, but there is a cost). The SMS address is basically an e-mail address in a specific form—for instance, for a Verizon number it is typically cellnumber@vtext.com, such as 7778675309@vtext.com. Each different carrier has its own domain for this.
If you have a cell number, you can get the corresponding SMS address using
https://freecarrierlookup.com
(Again, there are services that will do this in bulk for a fee). You can use that to build up (for instance) an Excel spreadsheet in the proper form for the input to the WinTD e-mail operation. Note that you can use the same file for multiple tournaments—whether someone gets a text depends upon whether they (or the team they represent) is in the tournament.